stable isotopes δ18o and δ13c trace and minor element compositions of recent scleractinians and last glacial bivalves at the santa maria di leuca deep water coral province ionian sea special issue the aplabes programme physical chemical and biological characterization of deep water coral ecosystems from the ionian sea mediterranean 16 pages 13 figures 3 tables 2 appendix

erosional processes topographic length scales and geomorphic evolution in arid climatic environments the lluta collapse northern chile the lluta collapse of northern chile is one of the oldest recognizable landslides 2 5 ma in a hyperarid continental setting this paper develops a conceptual landscape evolution model of the lluta collapse and analyzes the controls of mass wasting and erosion sediment transport in channels on the topographic development the data presented here imply that high relief along a topographic scarp surface fracturing elevated groundwater table during a more humid climate and an aquitard underlying permeable ignimbrites are preparatory causal factors for landsliding 2 5 ma ago a strong seismic event then possibly resulted in the displacement of ca 26 km3 of mass subsequent modification of the landslide scar occurred by backward erosion resulting in the establishment of a dendritic drainage network and the removal of an additional ca 24 km3 of material it appears that this mass was produced by mass wasting in the headwaters and exported by high concentrated debris flows in channels in addition morphometric information suggest that whereas the geometrical development of the lluta collapse has been controlled by gravitational mass wasting the rates of the development of this geomorphic unit have been limited by the export rates of mass and hence by the transport capacity of the flows

stable sr isotope sr ca mg ca li ca and mg li ratios in the scleractinian cold water coral lophelia pertusa the aragonitic skeletons of scleractinian cold water corals can serve as valuable archives in paleoceanographic studies the potential of 88 86sr sr ca mg ca li ca and mg li ratios of the cold water coral lophelia pertusa to record intermediate water mass properties has been investigated here we used samples from several locations along the european continental margin spanning a large temperature range from 6 to 14 c stable strontium isotope measurements were carried out with the recently developed double spike tims technique and our results differ from those obtained with less precise methods in contrast to the strong positive relationship with temperature of previous studies our results suggest that 88 86sr measured in scleractinian cold water corals is not controlled by seawater temperature but reflects the sr isotopic composition of seawater with an offset of 88 86sr 0 196 as found in previous studies the elemental ratios sr ca li ca and mg li measured in corals are significantly related to water temperature and do not correlate with salinity moreover sr ca ratios in l pertusa display the expected inverse correlation with temperature however the variance in the sr ca data severely limits the accuracy of paleotemperature estimates the li ca and mg ca ratios reveal other influences besides temperature such as ph and or growth or calcification rate however corresponding mg li ratios in l pertusa are more tightly related to temperature as they remove these secondary effects in particular the mg li ratio in l pertusa may serve as a new promising paleotemperature proxy for intermediate water masses our dataset represents the most extensive geochemical examination of l pertusa to date revealing a temperature sensitivity of 0 015 mol mmol c for mg li however using this temperature dependence and the precision of 5 3 2sd only temperature variations larger than 1 5 c can be resolved with 95 confidence

distribution of magnesium in coral skeleton ion micro probe imaging of the aragonite skeleton of pavona clavus a massive reef building coral shows that magnesium and strontium are distributed very differently in contrast to strontium the distribution of magnesium is strongly correlated with the fine scale structure of the skeleton and corresponds to the layered organization of aragonite fibers surrounding the centers of calcification which have up to ten times higher magnesium concentration this indicates a strong biological control over the magnesium composition of all structural components within the skeleton magnesium may be used by the coral to actively control the growth of the different skeletal crystal components

li ca in multiple species of benthic and planktonic foraminifera thermocline latitudinal and glacial interglacial variation li ca ratios were measured in planktonic and benthic foraminifera from a variety of hydrographic settings to investigate the factors influencing lithium incorporation into foraminiferal tests including temperature dissolution pressure and interspecies differences down core measurements of planktonic orbulina universa globigerinoides ruber and globigerinoides sacculifer and benthic foraminifera calcitic cibicides wuellerstorfi and aragonitic hoeglandina elegans show a systematic variation in li ca with 18o through the last glacial interglacial transition all species examined exhibit an increase in li ca between 14 to 50 from the holocene to the last glacial maximum li ca generally increases with decreasing temperature as seen in a latitudinal transect of planktonic o universa and down slope benthic species along the bahama bank margins postdepositional dissolution possibly causes a decrease in planktonic foraminiferal li ca along the sierra leone rise and increased water depth causes a decrease in benthic foraminiferal li ca in the deep caribbean however none of these effects are sufficient to account for the observed glacial interglacial changes physiological factors such as calcification rate may affect the li ca content of foraminiferal calcite the calcification rate in turn may be a function of carbonate ion concentration of ambient ocean water this work shows that incorporation of lithium by foraminifera appears to be influenced by factors other than seawater composition and does not appear to be dominated by changes in temperature dissolution or pressure we hypothesize that the consistent increase in foraminiferal li ca during the last glacial maximum may be linked to changes in seawater carbonate ion concentration important parameters to be tested include calcification rate and foraminiferal test size and weight if foraminiferal li ca is dominantly controlled by calcification rate as a function of seawater carbonate ion concentration then li ca may act as a proxy of past atmospheric co2

effect of mineralogy salinity and temperature on li ca and li isotope composition of calcium carbonate li ca and li isotope ratios in marine and freshwater calcium carbonates are potential tracers of past environmental variables such as weathering intensity and temperature to make use of their potential requires full understanding of the fractionation of li ca and 7 li 6 li during growth of calcium carbonate this study improves such understanding with two sets of new measurements on inorganic calcites and aragonites precipitated over a range of salinity and on the test of benthic foraminifera formed at a range of temperatures li ca in inorganic calcite increases by a factor of four as salinity increases from 10x to 50x inorganic aragonite demonstrates no significant change in li ca over the same salinity range the difference in behaviour is probably due to the incorporation mechanism of li substitution of li in the ca 2 site in aragonite makes growth solution li ca the key variable while interstitial incorporation of li in calcite means that the growth solution li concentration is more important compared to the growth solution 7 li 6 li is c3x lower in calcite and c11x lower in aragonite with no relationship to salinity for either mineral similar isotope fractionation to these inorganic experiments are observed for biogenically produced calcite foraminifera and aragonite corals this suggests little biological control during li incorporation into biogenic calcium carbonates the difference in fractionation between calcite and aragonite is consistent with an equilibrium isotope fractionation reflecting different incorporation mechanisms for li into the two minerals four samples of the benthic foraminifera uvigerina precipitated over a temperature range of 14 8c have li ca ranging from 18 5 to 13 1 amol mol the ratio is inversely related to temperature with a sensitivity of 2 5f0 8 per 8c this sensitivity is similar to that observed in a previous study of foraminiferal li ca but about half that observed during inorganic calcite growth the large variability in both li ca and temperature sensitivity exhibited between various foraminifera species suggests an additional control on calcite li ca apart from those of salinity and temperature observed in this study d 2004 elsevier b v all rights reserved

reactivation of basement faults beneath volcanoes a new model of flank collapse in order to explain the presence of voluminous volcanic debris avalanche deposits around a stratovolcano reactivation of vertical faults beneath a volcanic cone has been tested using analogue models reactivation of a single vertical fault beneath a cone generates a normal fault and an upturning of the layers creating a bulge on the flank the upturning induces a flank collapse characterized by a typical horseshoe shaped scar called an avalanche caldera reactivation of two vertical faults beneath a cone also generates a normal fault and a summit bulge this bulge may result from the movement along a reverse fault a large collapse is generated within the angle created by the two vertical faults the angle of the collapse can be up to 140 whereas this angle is typically 120 for a dome intrusion collapse is instantaneous and is favoured by the presence of ductile layers ash and pumice formations in the example considered in a stratovolcano complex the model may be applicable to volcanoes in a state of dormancy or extinction in regions with active regional tectonism we suggest this mechanism of collapse in the case of the cantal stratovolcano massif central france to explain the presence of voluminous volcanic debris avalanche deposits around this volcano

controls on sr ca in benthic foraminifera and implications for seawater sr ca during the late pleistocene changes in the sr to ca ratio of sea water have important implications for the interpretation of past climate it has proven difficult to interpret sr ca of foraminiferal calcite as a measure of seawater sr ca or as reflecting the influence of deep water carbonate ion saturation co 32 on the incorporation of sr into benthic foraminiferal carbonate here we address this issue by measurements of paired benthic foraminiferal sr ca and b ca a proxy for deep water delta co 32 for core tops from the global ocean and three down cores at different settings during the last glacial textendash interglacial cycle these new data suggest a significant control of deep water delta co 32 on benthic foraminiferal sr ca and that down core shell sr ca variations can be largely accounted for by past deep water delta co 32 changes we conclude that seawater sr ca has likely remained near constant on glacial textendash interglacial timescales during the late pleistocene in agreement with model results with due caution benthic sr ca may be used as an auxiliary proxy for deep water delta co 32 if seawater sr ca is constant

mg ca sr ca and ca isotope ratios in benthonic foraminifers related to test structure mineralogy and environmental controls we analysed mg ca sr ca and ca isotope ratios of benthonic foraminifers from sediment core tops retrieved during several research cruises in the atlantic ocean in order to improve the understanding of isotope fractionation and element partitioning resulting from biomineralisation processes and changes in ambient conditions species include foraminifers secreting tests composed of hyaline low magnesium calcite porcelaneous high magnesium calcite as well as aragonite our results demonstrate systematic isotope fractionation and element partitioning patterns specific for these foraminiferal groups calcium isotope fractionation is similar in porcelaneous and hyaline calcite tests and both groups demonstrate the previously described anomaly with enrichment of heavy isotopes around 3 4 degrees c gussone and filipsson 2010 calcium isotope ratios of the aragonitic species hoeglundina elegans on the other hand are about 0 4 parts per thousand lighter compared to the calcitic species which is in general agreement with stronger fractionation in inorganic aragonite compared to calcite however the low and strongly variable sr content suggests additional processes during test formation and we propose that transmembrane ion transport or a precursor phase to aragonite may be involved porcelaneous tests composed of high mg calcite incorporate higher amounts of sr compared to hyaline low mg calcite in agreement with inorganic calcite systematics but also porcelaneous tests with reduced mg ca show high sr ca while calcium isotopes sr ca and mg ca in benthonic foraminifers primarily appear to fractionate and partition with a dominant inorganic control delta ca 44 40 temperature and growth rate dependencies of benthonic foraminifer tests favour a dominant contribution of light ca by transmembrane transport relative to unfractionated seawater ca to the calcifying fluid thus controlling the formation of foraminiferal delta ca 44 40 and sr ca proxy signals c 2015 elsevier ltd all rights reserved less

pliocene uplift of the massif central france constrained by the palaeoelevation quantified from the pollen record of sediments preserved along the cantal stratovolcano murat area the french massif central is a key basement relief this region experienced an intense period of alkaline volcanism beginning with the cantal stratovolcano at 11 ma and ending at 3 ma to quantify the palaeoelevation of the cantal stratovolcano and to replace it in the frame of the uplift history of the massif central we first reconstructed the vegetation and climate based on a pollen analysis of the murat diatomites which were deposited in a maar lake the vegetation was organized in three different belts a glyptostrobus swamp around the lake a mixed forest and at higher altitudes a conifer forest the climate estimated using the climatic amplitude method indicates temperatures between 11 4 and 17 c using these estimates and comparison with contemporaneous sites we infer a palaeoelevation for murat between 710 and 930 m a s l this site was therefore uplifted by 130 to perhaps 350 m during the early pliocene leading to a reorganization of the drainage pattern and the capture of rivers flowing from the northern edge of the massif central towards the atlantic ocean our study confirms that the cantal stratovolcano was a high volcano 2500 m before its progressive dismantling during glacial episodes in the pleistocene

mg ca temperature proxy in benthic foraminifera new calibrations from the florida straits and a hypothesis regarding mg li 1 over the past decade the ratio of mg to ca in foraminiferal tests has emerged as a valuable paleotemperature proxy however large uncertainties remain in the relationships between benthic foraminiferal mg ca and temperature mg ca was measured in benthic foraminifera from 31 high quality multicore tops collected in the florida straits spanning a temperature range of 5 8 to 18 6 c new calibrations are presented for uvigerina peregrina planulina ariminensis planulina foveolata and hoeglundina elegans the mg ca values and temperature sensitivities vary among species but all species exhibit a positive correlation that decreases in slope at higher temperatures the decrease in the sensitivity of mg ca to temperature may potentially be explained by mg ca suppression at high carbonate ion concentrations it is suggested that a carbonate ion influence on mg ca may be adjusted for by dividing mg ca by li ca the mg li ratio displays stronger correlations to temperature with up to 90 of variance explained than mg ca alone these new calibrations are tested on several last glacial maximum lgm samples from the florida straits lgm temperatures reconstructed from mg ca and mg li are generally more scattered than core top measurements and may be contaminated by high mg overgrowths the potential for mg ca and mg li as temperature proxies warrants further testing

el ventorrillo a paleostructure of popocatepetl volcano insights from geochronology and geochemistry volcan popocatepetl mexico was constructed over the remains of a volcanic paleostructure based on fieldwork 40ar 39ar dating u pb dating and geochemistry we have determined the age chemistry and location of this paleostructure and named it el ventorrillo most remnants of el ventorrillo are covered by deposits from subsequent activity of popocatepetl except for the el abanico scarp and the barranca de nexpayantla where the stratigraphy of el ventorrillo eruptive products can be investigated inception of volcanism at el ventorrillo occurred at 331 10 ka with emission of the nexpayantla andesitic lavas and continued with extrusion of the yoloxochitl 267 31 ka and microwave 227 6 ka domes intrusion of dikes occurred at 298 94 and 230 3 ka activity at el ventorrillo continued with the emission of lavas that built the el abanico scarp 193 29 to 96 8 ka and continued until the tutti frutti eruption destroyed the cone 14 1 kyr ago el ventorrillo magmas produced rocks divided into two mineralogical groups the first group contains biotite amphibole rich rocks and the second group consists of biotite amphibole free lavas the rocks that contain biotite and amphibole are older than 198 13 ka whereas the rocks with no hydrous phases are younger than 227 6 ka and contain skarn and granodiorite xenoliths we interpret the change to an anhydrous mineral assemblage and the occurrence of skarn and granodiorite xenoliths as evidence for the formation of a new shallower reservoir a granodiorite xenolith was chosen for 40ar 39ar dating and u pb zircon analyses the u pb method yielded an age of 540 110 ka and the 40ar 39ar an age of 109 24 ka these ages are interpreted to indicate granodiorite crystallization 540 110 ka which metamorphosed the calcareous basement beneath popocatepetl into skarn and an influx of magma 109 24 ka that reheated the granodiorite major and trace elements sr nd and pb isotopic compositions and textural analyses of plagioclase show that el ventorrillo magmas were moderately modified by mixing with more mafic magmas and that assimilation of the calcareous basement was negligible

environmental and biological controls on mg and li in deep sea scleractinian corals abstract deep sea scleractinian corals precipitate aragonite skeletons that provide valuable archives of past ocean conditions during calcification biological mediation causes variability in trace metal incorporation and isotopic ratios of the aragonite such that signals caused by environmental controls can be overwhelmed this complicates the interpretation of geochemical proxies used for paleo reconstructions in this study we examine the environmental controls on the mg li ratio of 34 individuals from seven genera of deep sea scleractinian corals desmophyllum balanophyllia caryophyllia enallopsammia flabellum trochocyanthus and lophelia in addition we examine the microscale distributions of mg and li in desmophyllum and balanophyllia using laser ablation inductively coupled plasma mass spectrometry la icp ms both mg ca and li ca ratios increased by more than a factor of two in the center of calcification regions compared to the outer fibrous regions of the coral skeleton as a result replicate 10 mg subsamples of coral show less variability in the mg li ratio than mg ca microscale mg and li results are consistent with rayleigh type incorporation of trace metals with additional processes dominating the composition within centers of calcification comparison of mg li to seawater properties near the site of collection shows that the ratio is not controlled by either carbonate ion or salinity it appears that temperature is the major control on the mg li ratio for all 34 samples the temperature correlation r2 0 62 is significantly better than for mg ca r2 0 06 for corals of the family caryophyllidae the r2 value increases to 0 82 with the exclusion of one sample that was observed to have an altered chalky texture despite this excellent correlation the scatter in the data suggests that the mg li ratio of deep sea corals cannot be used to reconstruct temperature to better than approximately 1 6 c without better temperature control and additional calibration points on modern coral samples

multiple related flank collapses on volcanic oceanic islands evidence from the debris avalanche deposits in the orotava valley water galleries tenerife canary islands abstract catastrophic flank collapses are common on oceanic islands of volcanic origin and often recognizable from the resulting morphology as large u shaped embayments however post collapse volcanic activity can infill such features thereby obscuring them this study takes advantage of a dense network of long sub horizontal galleries for groundwater extraction in the flank collapse structure of the orotava valley tenerife canary islands this impressive landform is located in the overlapping zone of the ne rift and the canadas edifice of this volcanic island three debris avalanche deposits dads have been identified inside the waterworks bored into the valley s western sector the deeper layer the lower dad l dad was previously described under the local name of mortalon this deposit lies unconformably over older volcanic rocks where a prominent shear zone is developed here interpreted as the detachment plane of a massive rockslide the l dad was therefore produced during the large failure event the orotava landslide ol which carved the depression two younger dads much smaller in volume and not previously described were also identified in the underground strata the intermediate i dad and upper dad u dad both correlate well with the thick breccia deposits cropping out at the base of the marine cliff along the western coast of the valley the i dad and u dad are conformably intercalated between the lava flows and other volcanics infilling the depression and their bases are erosive depositional features without structural deformation zones below them their stratigraphic setting and geometrical reconstruction indicate that both deposits were emplaced after the valley was formed by the ol event in two successive failures here called western orotava landslides wols the younger called wol 2 was dated at 494 22 ka using the 40ar 39ar method these two subaerial failures affected the upper eastern flank of the canadas iii edifice previously destabilized when the ol failure event carved a steep wall at its foot the western lateral escarpment of the orotava valley

landslides on charon abstract we investigated five large landslides identified in the serenity chasma region of charon the identification of these landslides involved a search for these features in images taken by cameras onboard the new horizons spacecraft various landslide properties were analyzed based on their morphologies using a digital terrain model of the region we found that landslides are confined to the walls of the large normal fault scarps that make up serenity chasma based on extensive landslide runout lengths l relative to their drop heights h we classified these features as long runout landslides by analyzing their geometries we estimated the friction coefficients of the landslide material h l to be between 0 15 to 0 31 and the runout efficiencies l h to be between 3 2 and 6 8 we also estimated that the specific energy released during landslide motion ranged from 0 8 to 1 3 kj kg 1 these amounts of energy were too low to have generated significant melt around landslide particles

a simple biomineralization model to explain li mg and sr incorporation into aragonitic foraminifera and corals abstract in contrast to li ca and mg ca li mg is strongly anticorrelated with temperature in aragonites precipitated by the benthic foraminifer hoeglundina elegans and a wide range of scleractinian coral taxa we propose a simple conceptual model of biomineralization that explains this pattern and is consistent with available abiotic aragonite partition coefficients under this model the organism actively modifies seawater within its calcification pool by raising its ca2 using a pump that strongly discriminates against both li and mg2 rayleigh fractionation during calcification effectively reverses this process removing ca2 while leaving most li and mg2 behind in the calcifying fluid the net effect of these two processes is that li mg in the calcifying fluid remains very close to the seawater value and temperature dependent abiotic partition coefficients are expressed in the biogenic aragonite li mg ratio we further show that coral sr ca is consistent with this model if the ca2 pump barely discriminates against sr2 in h elegans the covariation of sr ca and mg ca requires either that the pump more strongly discriminates against sr2 or that cation incorporation is affected by aragonite precipitation rate via the mechanism of surface entrapment in either case li mg is minimally affected by such vital effects which plague other elemental ratio paleotemperature proxies

calcium isotope fractionation in modern scleractinian corals the 44ca 40ca ratios of cultured acropora sp and open ocean pavona clavus porites sp tropical reef corals are positively correlated with growth temperature the slope of the temperature fractionation relation is similar to inorganic aragonite precipitates however 44 40ca of the coral aragonite is offset from inorganic and sclerosponge aragonite by about 0 5 this offset can neither be explained by the very fast biologically controlled calcification of scleractinian corals nor as a consequence of calcification from a partly closed volume of fluid as corals actively transport calcium through several cell layers to the site of calcification the most likely explanation for the offset is a biologically induced fractionation our results indicate a limited use of ca isotopes in scleractinian corals as temperature proxy

flank collapse at mount wrangell alaska recorded by volcanic mass flow deposits in the copper river lowland an areally extensive volcanic mass flow deposit of pleistocene age known as the chetaslina volcanic mass flow deposit is a prominent and visually striking deposit in the southeastern copper river lowland of south central alaska the mass flow deposit consists of a diverse mixture of colorful variably altered volcanic rocks lahar deposits glaciolacustrine diamicton and till that record a major flank collapse on the southwest flank of mount wrangell the deposit is well exposed near its presumed source and thick continuous stratigraphic exposures have permitted us to study its sedimentary characteristics as a means of better understanding the origin significance and evolution of the deposit deposits of the chetaslina volcanic mass flow in the chetaslina river drainage are primary debris avalanche deposits and consist of two principal facies types a near source block facies and a distal mixed facies the block facies is composed entirely of block supported shattered and fractured blocks with individual blocks up to 40 m in diameter the mixed facies consists of block sized particles in a matrix of poorly sorted rock rubble sand and silt generated by the comminution of larger blocks deposits of the chetaslina volcanic mass flow exposed along the copper tonsina and chitina rivers are debris flow deposits that evolved from the debris avalanche component of the flow and from erosion and entrainment of local glacial and glaciolacustrine diamicton in the copper river lowland the debris flow deposits were probably generated through mixing of the distal debris avalanche with the ancestral copper river or through breaching of a debris avalanche dam across the ancestral river the distribution of facies types and major element chemistry of clasts in the deposit indicate that its source was an ancestral volcanic edifice informally known as the chetaslina vent on the southwest side of mount wrangell a major sector collapse of the chetaslina vent initiated the chetaslina volcanic mass flow forming a debris avalanche of about 4 km 3 that subsequently transformed to a debris flow of unknown volume

mg ca sr ca and u ca ratios of a porites coral from sanya bay hainan island south china sea and their relationships to sea surface temperature high resolution mg ca sr ca and u ca ratios are reported in the skeleton of porites sp collected from sanya bay on the south coast of the hainan island china using inductively coupled plasma mass spectrometry combined with isotope dilution technique icp ms id the coralline mg ca ratios covary with sea surface temperatures sst for the 10 year interval giving the relationship between mg ca and sst as t degrees c 14 13 0 31 8 846 0 068 x 10 3 mg ca with the mean square weighted deviation mswd of 9 7 using this equation we are able to reconstruct sst record with a precision better than 0 5 degrees c several sr ca and u ca ratios show poor linear relationships with the measured sst this study indicates that the growth rates of the coral do not significantly affect coralline mg ca sr ca and u ca ratios however the high meteoric precipitation in this area which may cause a heavy run off from the island may change seawater sr ca and u ca ratios and ruin the relationships between coralline sr ca or u ca ratios and sst this implies that in coastal areas like hainan coralline mg ca ratios are valid for reconstructing the sst records but sr ca and u ca ratios may be suspected c 2000 elsevier science b v all rights reserved

empirical assessment of coral sr ca and mg ca ratios as climate proxies using colonies grown at different temperatures 1 coral strontium calcium sr ca and magnesium calcium mg ca ratios might be useful for reconstructing past sea surface temperature sst in tropical oceans where instrumental data are limited however the link between coral skeletal trace elements and sst is disputed and biological factors such as skeletal growth rate may also affect trace elements in a coral we studied the relationships between growth rate and sst and sr ca and mg ca ratios using corals porites spp cultured in thermostated tanks sr ca was controlled primarily by sst while mg ca mainly reflected the growth rate with negligible contribution from species on both the variations these relationships are consistent with modeled results of cation partitioning during aragonite crystal formation

catastrophic debris avalanche from ancestral mount shasta volcano california a debris avalanche deposit extends 43 km northwestward from the base of mount shasta across the floor of shasta valley california where it covers an area of at least 450 km 2 the surface of the deposit is dotted with hundreds of mounds hills and ridges all formed of blocks of pyroxene andesite and unconsolidated volcaniclastic deposits derived from an ancestral mount shasta individual hills are separated by flat topped laharlike deposits that also form the matrix of the debris avalanche and slope northwestward about 5 m km radiometric ages of rocks in the deposit and of a postavalanche basalt flow indicate that the avalanche occurred between about 300 000 and 360 000 yr ago an inferred average thickness of the deposit plus a computed volume of about 4 km 3 for the hills and ridges indicate an estimated volume of about 26 km 3 making it the largest known quaternary landslide on earth

long term impacts of the 1997 1998 bleaching event on the growth and resilience of massive porites corals from the central red sea we would like to acknowledge the team at kaust for their support knowledge and hospitality while the coral cores were being retrieved with special thanks to anna roik for her input in this paper we thank the technical staff of agfior kai rankenburg and anne marin nisumaa comeau for their laboratory expertise this research was supported by king abdullah university of science and technology kaust and by funding provided by an arc laureate fellowship lf120100049 awarded to professor malcolm mcculloch and the arc centre of excellence for coral reef studies ce140100020 all the geochemical data generated are available at https doi pangaea de 10 1594 pangaea 901186

a study of the taisho lahar generated by the 1926 eruption of tokachidake volcano central hokkaido japan and implications for the generation of cohesive lahars abstract understanding the generation mechanisms of lahars is important for improving volcanic hazard assessments the taisho lahar tl was generated during the 1926 eruption of tokachidake volcano japan and was considered a typical snowmelt lahar caused by the runout of hot debris onto a snow covered slope a similar mechanism produced a huge mud flow during the 1985 eruption of nevado del ruiz colombia however the origin of water in such lahars remains a controversial topic because the calculated water mass is based on the assumption that all of the snow on the runout area of the tl was melted although this is much less than the estimated water volume in the tl estimated by previous studies i have re examined proximal deposits of the tl and their paleomagnetic characteristics in order to better understand the eruption sequence and formation of the tl the tl produced two debris avalanche deposits and a surge like deposit that had relatively high emplacement temperature 350 c the deposits are composed of hydrothermally altered andesitic gravel sand and mud the high clay content 3 5 wt clay in the 6 m 3 water beneath the active crater this study indicates that hydrothermal system explosions can trigger cohesive lahars that contain both snow melt and hydrothermal pore water and this indicates the need to monitor hydrothermal systems

coral sr u thermometry coral skeletons archive past climate variability with unrivaled temporal resolution however extraction of accurate temperature information from coral skeletons has been limited by vital effects which confound and sometimes override the temperature dependence of geochemical proxies we present a new approach to coral paleothermometry based on results of abiogenic precipitation experiments interpreted within a framework provided by a quantitative model of the coral biomineralization process decarlo et al 2015a investigated temperature and carbonate chemistry controls on abiogenic partitioning of sr ca and u ca between aragonite and seawater and modeled the sensitivity of skeletal composition to processes occurring at the site of calcification the model predicts that temperature can be accurately reconstructed from coral skeleton by combining sr ca and u ca ratios into a new proxy which we refer to hereafter as the sr u thermometer here we test the model predictions with measured sr ca and u ca ratios of 14 porites sp corals collected from the tropical pacific ocean and the red sea with a subset also analyzed using the boron isotope 11b ph proxy observed relationships among sr ca u ca and 11b agree with model predictions indicating that the model accounts for the key features of the coral biomineralization process by calibrating to instrumental temperature records we show that sr u captures 93 of mean annual temperature variability 26 30 c and has a standard deviation of prediction of 0 5 c compared to 1 c using sr ca alone the sr u thermometer may offer significantly improved reliability for reconstructing past ocean temperatures from coral skeletons

depositional features and transportation mechanism of valley filling iwasegawa and kaida debris avalanches japan the depositional features of two valley filling debris avalanche deposits were studied to reveal their transportation and depositional mechanisms the valley filling iwasegawa debris avalanche deposit ca 0 1 km3 is distributed along the valleys at the southeastern foot of tashirodake volcano northern honshu japan debris avalanche blocks range in size from 0 3 km3 is distributed along the valleys at the eastern southeastern foot of ontake volcano central japan debris avalanche blocks range in size from 25 m proximally to 7 m in the medial zone debris avalanche matrix percentages increase from 50 70 in the proximal zone to 80 in the distal zone the debris avalanche matrix is more abundant 80 90 at the bottom part of the deposit deformation structures observed in the debris avalanche blocks include elongation folding conjugate reverse faults and numerous minor faults in unconsolidated materials lithic components within the debris avalanche matrix tend to have a higher percentage of plucked clasts from the adjacent underlying formations a bingham plug flow model is consistent with the transportation and depositional mechanisms of the valley filling debris avalanches in the plug of the debris avalanche fragile blocks were transported without major rupturing due to relatively small shear stresses in regions of small strain rate the debris avalanche matrix was mainly produced by shearing at the bottom and margins of the avalanche valley filling debris avalanches tend to have smaller debris avalanche blocks and larger amounts of debris avalanche matrix than do unconfined debris avalanches these differences may be due to disaggregation of debris avalanche blocks by shearing against valley walls and interaction between debris avalanche blocks and valley walls oriented wood logs and branches reverse grading of clasts at the base and a higher proportion of incorporated clasts at the base are interpreted to result from shearing along the bottom and valley walls

caldera formation at volcan colima mexico by a large large holocene volcanic debris avalanche abstract about 4 300 years ago 10 km 3 of the upper cone of ancestral volcan colima collapsed to the southwest leaving a horseshoe shaped caldera 4 km in diameter the collapse produced a massive volcanic debris avalanche deposit covering over 1550 km 2 on the southern flanks of the volcano and extending at least 70 km from the former summit the avalanche followed a steep topographic gradient unobstructed by barriers resulting in an unusually high area volume ratio for the colima deposit the apparent coefficient of friction fall height distance traveled for the colima avalanche is 0 06 a low value similar to those of other large volume deposits the debris avalanche deposit contains 40 75 angular volcanic clasts from the ancestral cone a small proportion of vesicular blocks that may be juvenile and in distal exposures rare carbonate clasts plucked from the underlying surface by the moving avalanche clasts range in size to over 20 m in diameter and are brecciated to different degrees pulverized and surrounded by a rock flour matrix the upper surface of the deposit shows prominent hummocky topography with closed depressions and surface boulders a thick coarse grained compositionally zoned scoria fall layer on the upper northeastern slope of the volcano may have erupted at the time of collapse a fine grained surge layer is present beneath the avalanche deposit at one locality apparently representing an initial blast event most of the missing volume of the ancestral volcano has since been restored at an average rate of 0 002 km 3 yr through repeated eruptions from the post caldera cone as a result the southern slope of volcan colima may again be susceptible to collapse over 200 000 people are now living on primary or secondary deposits of the debris avalanche and a repetition of this event would constitute a volcanic disaster of great magnitude ancestral volcan colima grew on the southern trenchward flank of the earlier and larger volcano nevado de colima trenchward collapse was favored by the buttressing effect of nevado the rapid elevation drop to the south and the intrusion of magma into the southern flank of the ancestral volcano other such trenchward younging paired volcanoes are known from mexico guatemala el salvador chile and japan the trenchward slopes of the younger cones are common sites for cone collapse to form avalanche deposits as occurred at colima and popocatepetl in mexico and at san pedro volcano in chile

temperature dependence of δ 7 li δ 44 ca and li ca during growth of calcium carbonate abstract lithium and calcium isotope ratios together with the li ca element ratio have been measured in calcites precipitated inorganically at temperatures ranging from 5 to 30 c and on seasonal growth bands from a coral these measurements indicate the potential uses of these three environmental proxies carbonate li isotopes are lighter than the solution from which they grow probably due to equilibrium fractionation this fractionation is not significantly influenced by temperature and because li is not involved in any known biological process this suggests that carbonates will provide a recorder for the past li isotope composition of natural waters and hence for past weathering conditions as has been observed previously for inorganic aragonite the ca isotopes in inorganic calcite are lighter than the growth solution and are only weakly dependent on temperature this confirms that the temperature dependence observed in some species of foraminifera geochem geophys geosyst 1 2001 reflects additional isotope fractionation due to biological processes during mineralization ca isotopes may therefore provide a powerful tool with which to investigate the processes of biomineralization finally li ca ratios in inorganic and biogenic carbonates increase as temperatures decrease with a sensitivity of 4 per c this temperature dependence of li ca may prove useful to assess past temperatures in cold environments such as the deep ocean

the contribution of landslides to landscape evolution in europe abstract after a review of some analytical and conceptual models of slope evolution with the intervention of mass movements a proposal is made of a series of indicators for the quantitative description of landscape evolution in relation to mass movements the ratio between landslide mobilisation rate and downwearing rate is proposed as a quantitative measure of the significance of mass movements in landscape evolution a subdivision of european regions with respect to their susceptibility to landsliding as a process of landscape evolution is proposed the role of landsliding for the evolution of landscape in some regions is described the data presented show that landsliding may in some cases be the main contributor to landscape change

the eastern flank of the merapi volcano central java indonesia architecture and implications of volcaniclastic deposits abstract merapi volcano in central java island is considered to be the most active and dangerous andesitic volcano in indonesia the volcanic history of merapi volcano is complex and often perturbed by frequent episodes of eruptive edifice building and subsequent erosion and collapse in this paper we present a detailed field literature and gis study of the well preserved eastern flank of merapi which has been spared from major eruptions in order to reconstruct the geologic and geomorphic history of the edifice here the most recent deposits arise from the remobilization of the old volcanic materials by lahar gravitational collapse of massive lava flow and local landslide processes in this study we describe the specific deposits and subsequent alteration and removal processes the stratigraphic analysis was performed with respect to the distinct phases of construction due to eruptions and dismantling of the volcano by erosion gravitational collapse and the associated local to distal re sedimentation based on gis analysis and field surveys a drainage network anomaly was detected in two main rivers the soka and the brambang rivers we infer that an apex fan of volcaniclastic material was deposited into a central paleo pusur river and explains the abnormal divergence of the rivers a new lithological 3d conceptual model is proposed based on the characterization of the lithological facies and their temporal and spatial evolution along the eastern flank of merapi volcano

ritter island volcano lateral collapse and the tsunami of 1888 summary in the early morning of 1888 march 13 roughly 5 km 3 of ritter island volcano fell violently into the sea northeast of new guinea this event the largest lateral collapse of an island volcano to be recorded in historical time flung devastating tsunami tens of metres high on to adjacent shores several hundred kilometres away observers on new guinea chronicled 3 min period waves up to 8 m high that lasted for as long as 3 h these accounts represent the best available first hand information on tsunami generated by a major volcano lateral collapse in this article we simulate the ritter island landslide as constrained by a 1985 sonar survey of its debris field and compare predicted tsunami with historical observations the best agreement occurs for landslides travelling at 40 m s 1 but velocities up to 80 m s 1 cannot be excluded the ritter island debris dropped little more than 800 m vertically and moved slowly compared with landslides that descend into deeper water basal friction block models predict that slides with shorter falls should attain lower peak velocities and that 40 ms 1 is perfectly compatible with the geometry and runout extent of the ritter island landslide the consensus between theory and observation for the ritter island waves increases our confidence in the existence of mega tsunami produced by oceanic volcano collapses two to three orders of magnitude larger in scale

intermediate water circulation changes in the florida straits from a 35 ka record of mg li derived temperature and cd ca derived seawater cadmium abstract we generated a high resolution ocean record of bottom water temperature and seawater cd from 546 m in the florida straits the record extends to 35 000 yr before present including all of marine isotope stages mis 2 and part of mis 3 previously seawater cadmium cdw has been used as a proxy for the strength of the atlantic meridional overturning circulation amoc during the last deglaciation we now consider the temperature and oxygen isotopic composition of seawater reconstructed from the same core in order to provide a fuller picture of water mass properties and circulation at this location during the last glacial maximum lgm cdw levels were generally low and a novel mg li derived temperature record reveals persistently cold temperatures 3 6 c two to three degrees colder than during the holocene or marine isotope stage 3 during the younger dryas and early heinrich stadial 1 cdw was low and temperatures were elevated compared with periods of inferred stronger amoc by contrast there is no indication of amoc variability over heinrich stadials 2 and 3 consistent with previous studies that conclude the amoc is less sensitive to freshwater forcing during glaciations than during the last deglaciation while there is some inconsistency between proxies cdw increases over some mis3 dansgaard oeschger interstadials providing qualified support for a strengthening in amoc this is similar to our previous finding that cdw tracks amoc variability during the deglaciation this study highlights the distinct nature of water masses and circulation during the lgm relative to the stadial weak amoc periods of the deglaciation and late mis 3

the giant submarine alika debris slide mauna loa hawaii probably represent multiple subsidence events before during and after the debris avalanches lower slopes of the slide contain distinctive lobate terraced deposits that are interpreted as having been emplaced more slowly prior to the debris avalanches estimated thicknesses of 50 200 m suggest volumes of 200 600 km 3 for the two lobes the combined volume of the entire slide and slump terrane is probably 1500 2000 km 3 the slide deposits predate a 13 ka coral reef and probably postdate the block faulted ninole basalt roughly dated as a few hundred thousand years old the alika slide or a similar deposit recognized on gloria images further north along the hawaiian ridge probably triggered a giant wave that washed 325 m high on lanai at about 100 ka slumping on mauna loa has been most intense adjacent to the large arcuate bend in its southwest rift zone as the rift zone migrated westward away from the growing kilauea volcano slumping events were probably triggered by seismic activity accompanying dike injection along the rift zone such massive slumps landslides and distal submarine turbidity flows appear to be widespread on the flanks of hawaiian volcanoes

constructive and destructive episodes in the building of a young oceanic island la palma canary islands and genesis of the caldera de taburiente the results of new field observations 23 new k ar determinations and sixteen previously published determinations provide the basis for the reconstruction of the subaerial volcanic history of the island of la palma after the seamount activity represented by the materials of the basal complex an eruptive phase between 2 0 and 1 3 ma formed a large shield a period of volcanic quiescence followed until around 1 ma during which a large lateral collapse partly destroyed the former edifice between 1 05 and 0 7 ma activity was renewed in the shield and a n s ridge was built in the southern part of the island around 0 7 ma two new large lateral collapses affected the western part of both edifices and they were followed by eruptions between 0 71 and 0 65 ma which built a new edifice that partly filled the depressions thus created the caldera de taburiente constitutes the eroded remnants of the depression formed in the northern shield from 0 65 ma to present activity has been restricted to the n s ridge which has continued to grow southwards there was a general n s migration of volcanic activity with time but in the shield the trend was northwest to southeast eruptive rates seem to have been fairly constant during the different eruptive phases considered between 0 15 and 0 37 km3 ka a very similar succession of constructive and destructive episodes has been obtained for the neighboring island of hierro but in this case the activity started around 0 8 ma and eruptive rates were about 0 5 km3 ka

sedimentary signatures of cyclic growth and destruction of stratovolcanoes a case study from mt taranaki new zealand abstract the long term behaviour of andesite stratovolcanoes is characterised by a repetition of edifice growth phases followed by collapse this cyclic pattern represents a natural frequency at varying timescales in the growth dynamics of stratovolcanoes worldwide around the 130 ka mt taranaki egmont volcano new zealand coastal cliff successions at 20 40 km distance comprise repeating packages of lithologically and sedimentologically distinctive mass flow deposits varying depositional mechanisms and source properties of these units record growth and collapse cycles of the central edifice these are used to construct a model for cyclic volcaniclastic sedimentation in the surrounds of stratovolcanoes during edifice construction phases thick packages of tabular predominantly monolithologic hyperconcentrated flow and debris flow deposits accumulate with intercalated tephra beds the mass flow units commonly contain large proportions of fresh pumice or juvenile lithic andesite intervals of quiescence separating eruptive periods are characterised by landscape re adjustment accompanied by deposition of fluvial and aeolian sediments along with steady accretion of medial ash in contrast brief episodes of destruction are marked by wide spread distinctively clay rich polylithologic debris avalanche deposits and related marginal debris flow units the growth stages can be terminated by an eruption triggered sector collapse or by external forces once the edifice exceeds a critical stable height or profile dependent on eruptive style and local geo tectonic conditions once the edifice becomes metastable regional tectonic earthquakes or shallow level intrusion events are likely triggers for collapse although the resulting debris avalanches represent the greatest individual hazard from such andesite stratovolcanoes their frequency is relatively low compared with other types of mass flows generated during edifice growth phases accurate forecasts of future hazard from mass flow events are therefore dependent on recognition of both the frequency of a stratovolcano s growth cycle and its current position in that cycle

textural features as indicators of debris avalanche transport and emplacement taranaki volcano the pungarehu debris avalanche deposit was emplaced by the largest known collapse of the proto taranaki volcano ca 25 000 calibrated cal years ago this debris avalanche deposit displays a highly contrasting sedimentary character between its proximal and distal reaches examination of the deposit granulometry sedimentary structures and microscopic particle attributes provides new insights into debris avalanche transport and internal evolution processes initial collapse of the proto taranaki volcano during this event occurred near the last glacial maximum with snow and ice cover and substantial groundwater present the collapsing sliding large blocks of edifice material megaclasts were highly fractured by the landslide generation and the depressurization event forming pervasive jigsaw textures as the megaclasts moved shear was focused in softer domains between the hardest lava dominated lithologies these crush and shear zones developed a complex pattern of relative motion between horizontal and vertical parts of the landslide rather than a simple basal shear zone that supported an upper pluglike mass the sheared zones concentrated in soft pyroclastic lithologies were areas of intense synflow fragmentation producing a proto interclast matrix between large blocks of coherent albeit jigsaw fractured lavas down flow the interclast matrix component increased to become pervasive by 23 25 km from the source enveloping and preserving large megaclasts out to at least 30 km the most distal exposures limited by coastal erosion to 25 27 km show that the matrix was not completely water saturated with only superficial penetration of the sand dominated material into the margins of fractured lava domains which still contained central void space evidence of multiple generations of particle fracturing is seen under scanning electron microscopy of sand grade clasts with initial decompression fractures crosscut by later cracks pits and scratches produced by collisional and frictional processes during transport the findings from this study help to explain the formation of the highly irregular topography of debris avalanche deposits with chaotically distributed and probably temporary zones of shear developing where softer lithologies occur in a collapsing mass thus leading to differential velocity profiles of portions of the flowing mass in vertical and horizontal planes

influence of detachment layer thickness on style of thin skinned shortening abstract there are several parameters which may determine whether detachment folds or thrust faults develop in thin skinned compressional systems a fundamental but little publicised parameter is apparent from consideration of detachment fold growth as a detachment fold amplifies its core must be filled by redistribution of ductile material if the mobile material were insufficient to supply the volume required by the fold core through redistribution fold growth would be inhibited and eventually faulting would occur the volume of a detachment fold core is compared here with the volume of available underlying mobile material for various amounts of shortening and sizes of fold the occurrence of detachment folds versus thrusts in several compressional belts is successfully predicted by this relationship

the source of ions for biomineralization in foraminifera and their implications for paleoceanographic proxies the global carbon cycle is strongly perturbed by fossil fuel burning leading to atmospheric co2 increase climatic warming followed by polar ice melting and global sea level rise are predicted due to the greenhouse effect of increasing co2 in the atmosphere houghton et al 1995 the ocean plays a major role in neutralizing the excess co2 because the amount of inorganic carbon available for exchange with the atmosphere in the ocean is approximately 50 60 times larger than in the atmosphere e g siegenthaler and sarmiento 1993 the bulk of the atmospheric co2 excess will eventually be neutralized by caco3 dissolution in the deep marine environment this is however is a relatively slow process that operates on the time scale of ocean circulation 1000 yrs and is therefore causing an accumulation of co2 in the atmosphere this phenomenon will result in potentially severe consequences to the well being of global ecological systems obviously the scientific attention of many biogeochemists is focused on processes controlling the response of the marine system to changes in atmospheric co2 concentrations e g archer and maier reimer 1994 broecker 1997 sigman and boyle 2000 berger 2002 foraminifera corals and coccolithophores in the global carbon cycle there are four dominant processes involved in neutralizing the excess atmospheric co2 in the ocean these are 1 gas exchange at the air sea interface and reaction with the carbonate ion to form bicarbonate 2 net primary productivity 3 caco3 production and dissolution and 4 ocean circulation most of these processes are biologically mediated and may have special importance in shallow tropical environments where the exchange with the atmosphere is more direct in this review we address the mechanism of biomineralization in one of the major groups that precipitates caco3 in the ocean the foraminifera as we will show this group

from deep seated slope deformation to rock avalanche destabilization and transportation models of the sierre landslide switzerland abstract sackung is a widespread post glacial morphological feature affecting alpine mountains and creating characteristic geomorphological expression that can be detected from topography over long time evolution internal deformation can lead to the formation of rapidly moving phenomena such as a rock slide or rock avalanche in this study a detailed description of the sierre rock avalanche sw switzerland is presented this convex shaped postglacial instability is one of the larger rock avalanche in the alps involving more than 1 5 billion m3 with a run out distance of about 14 km and extremely low fahrboschung angle this study presents comprehensive analyses of the structural and geological characteristics leading to the development of the sierre rock avalanche in particular by combining field observations digital elevation model analyses and numerical modelling the strong influence of both ductile and brittle tectonic structures on the failure mechanism and on the failure surface geometry is highlighted the detection of pre failure deformation indicates that the development of the rock avalanche corresponds to the last evolutionary stage of a pre existing deep seated gravitational slope instability these analyses accompanied by the dating and the characterization of rock avalanche deposits allow the proposal of a destabilization model that clarifies the different phases leading to the development of the sierre rock avalanche

the 1741 oshima oshima eruption extent and volume of submarine debris avalanche oshima oshima is a small volcanic island southwest off hokkaido in japan sea the violent eruption on august 29 1741 caused a sector collapse of the north flank very destructive tsunami with 2000 casualties was also documented but the generation mechanism has been controversial volume of subaerial sector collapse about 0 4 km was considered too small to generate such a devastating tsunami we compile and analyze recently obtained swath bathymetry data around the island the volcano is more than 2 3 km high from ocean bottom with its base diameter of 18 km the total slide volume both subaerial and submarine is estimated as 2 4 km nearly an order of magnitude larger than the subaerial part to the north of island hummocky terrain of debris deposits extends in an area of 69 km with the total volume of 2 5 km a value similar to the total slide volume it is one of the largest debris avalanches in historic time and probably responsible to the tsunami generation

trace element proxies for surface ocean conditions a synthesis of culture calibrations with planktic foraminifera abstract the trace element composition of planktic foraminiferal calcite provides a useful means of determining past surface ocean conditions we have assembled the results of culture experiments for three species of symbiont bearing planktic foraminifera globigerinoides ruber globigerinoides sacculifer and orbulina universa and one symbiont barren species globigerina bulloides to evaluate their responses to temperature salinity ph carbonate ion and dissolved inorganic carbon dic growth conditions trace element ratios li ca b ca mg ca sr ca mn ca cd ca ba ca na ca and u ca were measured simultaneously on samples grown with the same culture techniques which provides robust relatable calibrations that may be used together in multi proxy paleoceanographic studies our data confirm that temperature is the dominant control on foraminiferal mg ca under the ranges of conditions studied and that the potential effects of salinity and co32 on mg ca of these tropical species across late pleistocene glacial cycles are relatively small carbonate system experiments suggest that sr ca may be useful for reconstructing large dic changes na ca increases with salinity in g ruber pink but not in g sacculifer as these emerging proxy relationships become more firmly established the synthesis of multiple trace element ratios may help paleoceanographers isolate the effects of different environmental parameters in paleo records calcification rates g day vary among species and do not respond consistently to any experimental parameter comparison of our calcification rates with those observed in inorganic calcite precipitation experiments suggest that foraminifera calcify 100 more slowly than inorganic calcites grown in similar solutions we suggest that calcification rate does not typically exert a dominant control on trace element partitioning in planktic foraminiferal calcite though it may play a role for some elements under certain circumstances differences in average growth rate cannot explain composition differences among species pointing to alternative controls that may be biological in origin

the non tropical coral cladocora caespitosa as the new climate archive for the mediterranean high resolution weekly trace element systematics abstract high resolution weekly laser ablation icp ms trace element analyses b sr u mg ba are reported for the scleractinian coral cladocora caespitosa collected from the northern adriatic sea geochemical ratios sr ca b ca mg ca u ca ba ca were measured in a 38 mm long 10 years growth external coralline portion wall region and generally exhibit a close relationship with the in situ measured weekly fortnightly data on sea surface temperature sst available for the last 6 years in particular b ca ratios tuned to fine scale variations in sst show a high degree of correlation r 0 856 n 136 with sst and indicate that coral calcification only occurs above a minimum temperature threshold of 14 16 c in addition the ranges of trace element variability are larger than those typically recorded in tropical corals consistent with the large seasonal variations in sst of the adriatic this study thus demonstrates the feasibility of extracting and exploiting high resolution geochemical records from non tropical corals such as c caespitosa as a proxy for sst

anthropogenic ocean warming and acidification recorded by sr ca li mg δ11b and b ca in porites coral from the kimberley region of northwestern australia abstract the impact of climate changes on corals living in naturally extreme environments is poorly understood but crucial to longer term sustainability of coral reefs here we report century long temperature sr ca and li mg and calcifying fluid cf carbonate chemistry 11b and b ca records for a long lived 1919 to 2016 porites coral from the high thermally variable kimberley region of northwestern australia we investigate how increasing temperatures and ocean acidification are manifested in the carbonate chemistry of coral s cf and impacts of climate change on calcification using sr ca and li mg multiproxy we show that annual temperature in the nearshore kimberley exhibited a gradual increase 0 009 0 003 c yr from the 1920s onward however for the most recent years 2000 2015 more rapid summer warming 0 05 0 01 c yr are registered indicative of intensified warming despite that we find no significant trend for calcification rate of this coral over the past century as well as normal seasonal variability in coral s cf carbonate chemistry importantly the coral s ability to concentrate inorganic carbon seems to be affected by recent warming with reduced diccf observed during 2008 to 2015 while the minimally affected phcf acts to compensate the decreases of diccf with the calcification rate showing only slight decrease additionally we also find that ocean acidification has clearly led to the long term reduction in the ph of the cf

the cohesive naranjo debris flow deposit 10 km3 a dam breakout flow derived from the pleistocene debris avalanche deposit of nevado de colima volcano mexico abstract mass movement processes on volcanic terrains such as landslides and debris avalanches can cause the obstruction of main drainages producing the formation of temporary dams a good example of this occurred 18 5 ka ago when the eastern flank of the nevado de colima volcano collapsed producing a debris avalanche deposit that was previously described as one of the largest in the world the deposit extended from the volcanic summit as far as the pacific coast 120 km away new stratigraphic sedimentological and componentry data suggest that the volcanic collapse of nevado de colima resulted in a debris avalanche that traveled 20 km southeast to the naranjo river there it crashed against a topographic barrier consisting of cretaceous limestones cerro la carbonera and the flow direction was diverted to the south down the naranjo river channel for another 25 km before the avalanche came to a halt the obstruction of the drainage produced a temporary dam that stored ca 1 km3 of water and deposited fluvial and slack water sediments some time after the damming the accumulated water sediment load was able to overtop the obstructing material and to release a breakout flow with a calculated initial flow discharge of 3 5 million m3 s the resulting flood cohesive debris flow followed the channel of the naranjo river and due to the high erodibility of the channel and introduction of substrate material the debris flow progressively increased its volume up to 10 km3 six times its initial volume this study highlights the relevance of evaluating the potential remobilization of debris avalanche deposits to initiate large magnitude cohesive debris flows therefore the hazard and risk analysis of future potential events of this nature must consider the pre eruption conditions and the topography surrounding a volcano

precise multielemental ratios in small foraminiferal samples determined by sector field icp ms inductively coupled plasma mass spectrometry icp ms holds two main advantages over other techniques for the measurement of foraminiferal elemental ratios 1 numerous trace metals may be precisely and simultaneously measured and 2 smaller samples may theoretically be used methods are presented for the precise determination of mg ca sr ca cd ca zn ca li ca u ca mn ca and fe ca by sector field icp ms analytical precision is largely independent of sample size over the range of 5 to 125 g caco3 eliminating the need for narrow target dilutions long term 1 precisions are as follows mg ca 0 54 sr ca 0 57 cd ca 1 8 zn ca 3 2 li ca 0 88 u ca 1 9 mn ca 0 97 and fe ca 1 4 for mg ca actual foraminiferal samples appear to give reliable results below 10 g caco3 postcleaning mass

in situ δ7li li ca and mg ca analyses of synthetic aragonites in situ secondary ion mass spectrometry sims analyses of 7li li ca and mg ca were performed on five synthetic aragonite samples precipitated from seawater at 25 c at different rates the compositions of 7li in bulk aragonites and experimental fluids were measured by multicollector inductively coupled plasma mass spectrometry mc icp ms both techniques yielded similar 7li in aragonite when sims analyses were corrected to calcium carbonate reference materials fractionation factors 7li 6li range from 0 9895 to 0 9923 which translates to a fractionation between aragonite and fluid from 10 5 to 7 7 the within sample 7li range determined by sims is up to 27 exceeding the difference between bulk 7li analyses of different aragonite precipitates moreover the centers of aragonite hemispherical bundles spherulites are enriched in li ca and mg ca relative to spherulite fibers by up to factors of 2 and 8 respectively the li ca and mg ca ratios of spherulite fibers increase with aragonite precipitation rate these results suggest that precipitation rate is a potentially important consideration when using li isotopes and elemental ratios in natural carbonates as a proxy for seawater composition and temperature

benthic foraminiferal li ca insights into cenozoic seawater carbonate saturation state benthic foraminiferal li ca decreases down a norwegian sea holothermal depth transect suggesting that the saturation state of seawater with respect to calcium carbonate influences foraminiferal li ca benthic foraminiferal li ca increases by 17 across the glaciation event in the early oligocene which likely reflects the increase in seawater saturation state evidenced by the concomitant deepening of the calcite compensation depth following the establishment of the antarctic ice sheet benthic foraminiferal li ca bears a remarkable resemblance to the estimated oxygen isotopic composition of seawater suggesting that during this time seawater saturation was largely controlled by glacioeustatically driven changes in shallow water carbonate accumulation rates

cellular calcium pathways and isotope fractionation in emiliania huxleyi the marine calcifying algae emiliania huxleyi coccolithophores was grown in laboratory cultures under varying conditions with respect to the environmental parameters of temperature and carbonate ion concentration co32 concentration the ca isotope composition of e huxleyi s coccoliths reveals new insights into fractionation processes during biomineralization the temperature dependent ca isotope fractionation resembles previous calibrations of inorganic and biogenic calcite and aragonite unlike inorganically precipitated calcite the co32 concentration of the medium has no significant effect on the ca isotope composition of the coccoliths these results indicate a decoupling of the chemical properties of the bulk medium and the calcifying vesicle cellular ca pathways of e huxleyi indicate that fractionation cannot occur at the crystal surface as occurs during inorganic precipitation the dominant processes leading to the observed ca isotope fractionation pattern in e huxleyi are most likely the dehydration of the ca aquocomplex at the plasma membrane and the attachment of dissolved ca to proteins of ca channels the independence of ca isotope fractionation from co32 and the small temperature dependence of e huxleyi are also important for defining the isotopic signature of the oceanic ca sink since coccolithophores contribute to about half the global caco3 production a relatively uniform isotopic composition of the oceanic ca sink is further supported

evolution of the quaternary silicic volcanic complex of shiribetsu hokkaido japan an example of ignimbrite shield volcanoes in an island arc setting this paper describes the geology and eruptive history of a quaternary silicic volcanic complex at shiribetsu hokkaido japan with a focus on volcanic landforms produced by silicic explosive eruptions that were not associated with caldera collapse the shiribetsu volcanic complex comprises a dacitic pyroclastic plateau and an overlying dacitic central dome complex the pyroclastic plateau is 22 25 km in size 200 m high and consists of two ignimbrite units the km 1 and km 2 deposits sio2 67 68 wt total volume 10 km3 the central dome complex is 4 5 km wide rises to 650 m above the pyroclastic plateau and comprises two adjoining edifices which are east and west shiribetsu sio2 62 64 wt total volume 1 6 km3 east shiribetsu has a conical morphology whereas west shiribetsu comprises lava flows and a dome and has a large amphitheater a debris avalanche deposit volume 1 km3 extends from the amphitheater to the western foot of west shiribetsu a dacitic lava dome volume 0 2 km3 occurs within the amphitheater according to the stratigraphic relationships and new fission track dating the shiribetsu volcanic complex evolved as follows 1 dacitic explosive eruptions at ca 130 ka km 2 and 70 ka km 1 produced the pyroclastic plateau 2 effusive dacitic eruptions at 70 ka east shiribetsu and 60 ka west shiribetsu produced the central dome complex 3 sector collapse occurred at west shiribetsu at 50 60 ka and 4 lava dome formation within the amphitheater at 50 ka the evolution of the shiribetsu volcanic complex resembles that of ignimbrite shield volcanoes in the central andes shiribetsu may be the first identified example of ignimbrite shield volcanoes in an island arc setting we suggest that these are an independent class of explosive silicic volcanoes distinct from calderas and form above small magma chambers

pyroclastic density current from the 1888 phreatic eruption of bandai volcano ne japan abstract the great eruption of july 15 1888 at bandai volcano produced large phreatic explosions and a major debris avalanche toward the northern foot this eruption is characterized as follows 1 there was no significant precursor 2 the eruption and collapse of the volcanic edifice were triggered by an earthquake with a magnitude of about 5 3 the initial explosions were accompanied with a pyroclastic density current 4 the main explosive eruption quickly ceased a few minutes after the eruption began 5 a subsequent late stage plume rose buoyantly to a height of 5000 m falling with a heavy warm rain which generated a lahar and 6 ejected materials were made up wholly of pre existing rock fragments with no juvenile glass shards the main branch of the pyroclastic density current cascaded from the summit for a distance of 6 km along the biwazawa valley on the southeast flank the heim coefficient of the reconstructed energy line slope for the density current is 0 223 to 0 296 the estimated velocity using these values is less than 100 m s the density current deposit consists of normally graded parallel bedded or scour fill cross bedded thin layers of coarse ash and lapilli except for coarse massive breccia near the vent the sedimentary structures and grain size data suggest that the pyroclastic materials were transported in traction saltation and true suspension the estimated velocity is competent for transportation of the deposit the time sequence suggests that the seismic shocks and subsequent collapse of the edifice broke the confined hydrothermal system and caused the phreatic explosions the pressurized hydrothermal fluids had been presumably stored due to self sealing of the system because hydrothermal activities had been vigorous at the summit region until the july 15 seismic shocks collapse of the dry and dense initial eruption column generated the density current which spilled toward the opposite side of the crater along the topographic lows the change from the collapse to the late stage ascending plume results from a decrease in the rock fragment contents which made the plume light and wet this is because that a decrease in the fraction of rock fragments causes an increase in the fraction of steam produced within the plume the occurrence of the water flushed ash fall and lahar during the late stage eruption is consistent with this model

compositional and morphological features of aragonite precipitated experimentally from seawater and biogenically by corals abstract the morphology and composition of abiogenic synthetic aragonites precipitated experimentally from seawater and the aragonite accreted by scleractinian corals were characterized at the micron and nano scale the synthetic aragonites precipitated from supersaturated seawater solutions as spherulites typically 20 100 m in diameter with aggregates of sub micron granular materials occupying their centers and elongate fibrous needles radiating out to the edge using sr isotope spikes the formation of the central granular material was shown to be associated with high fluid ph and saturation state whereas needle growth occurred at lower ph and saturation state the granular aggregates have significantly higher mg ca and ba ca ratios than the surrounding fibers two types of crystals are identified in the coral skeleton aggregates of sub micron granular material and bundles of elongate fibrous crystals that radiate out from the aggregates the granular materials are found in centers of calcification and in fine bands that transect the fiber bundles they have significantly higher mg ca and ba ca ratios than the surrounding fibers the observed relationship between seawater saturation state and crystal morphology and composition in the synthetic aragonites was used as a framework to interpret observations of the coral skeleton we propose that coral skeletal growth can be viewed as a cyclical process driven by changes in the saturation state of the coral s calcifying fluids when saturation state is high granular crystals precipitate at the tips of the existing skeletal elements forming the centers of calcification as the saturation state decreases aragonitic fibres grow in bundles that radiate out from the centers of calcification

sea surface temperature and salinity reconstruction from coral geochemical tracers massive scleractinian corals secrete an aragonitic skeleton which incorporates a large array of chemical tracers corals present several advantages for palaeoclimate research they grow continuously and can live up to 1000 years they are easy to date and they can be sampled at high resolution weekly to monthly resolution both live and fossil corals can be collected in the field in the past two decades significant efforts have been made to identify robust tracers of sea surface temperature sst and salinity sss in corals to date sr ca and 18o are considered to be the most reliable sst tracers although changes in seawater 18o can significantly alter sst reconstructed from coralline 18o because these variations in seawater 18o can be linked to sss changes this initial problem can in fact be turned into an advantage and provide us with an sss tracer the sst component in the coral 18o signal can either be evaluated through sr ca measurements or in some case simply filtered out however there is still much uncertainty concerning the exact mode of incorporation of trace elements and stable isotopes into the coral skeleton the effects of growth rate light intensity feeding habits ph and water chemistry are still poorly documented a review of the strength and weaknesses of sr ca and 18o is presented together with some examples of sst and sss reconstructions other potential sst tracers are also reviewed it is expected that the ability to grow corals in aquarium under controlled conditions and that the development of sophisticated analytical techniques at the micrometric level should help us understand better the robustness of each tracers and the factors controlling their incorporation in coral aragonite

the montesbelos mass flow southern amazonian craton brazil a paleoproterozoic volcanic debris avalanche deposit the present contribution documents the extremely well preserved paleoproterozoic architecture of the montesbelos breccia named here for the first time which is interpreted as a rare example of a subaerial paleoproterozoic 1 85 ga granular dominated mass flow deposit few of which are recorded in the literature montesbelos deposit is part of the andesitic sobreiro formation located in the sao felix do xingu region southern amazonian craton northern brazil the large volume high variability of textural features presence of broken clasts angular low sphericity fragments mono to heterolithic character and the size of the outcrops point to a volcanic debris avalanche flow fluviatile sandy material and debris flows are associated with the deposit as a result of post depositional reworking processes

conditions favouring catastrophic landslides on tenerife canary islands catastrophic failures of volcano flanks represent one of the most hazardous geological phenomena these immense mass movements originate either by increasing the destabilizing forces driving forces or by reducing the strength of the materials involved or both the study of large volcanic landslides on tenerife suggests that the presence of weak residual soils palaeosols in combination with the pre existence of deep narrow canyons created by fluvial erosion have played a fundamental role in the initiation of large scale sector collapses of the volcanic edifice regardless of the triggering mechanism considered residual soils strongly reduce the material strength during undrained loading while pre existing canyons control the lateral limits of the landslide the existence of a wet climate in some sectors of the island favours these circumstances

an assessment of the sr ca ratio in shallow water hermatypic corals as a proxy for sea surface temperature the high precision measurement of the sr ca ratio in corals has the potential for measuring past sea surface temperatures at very high accuracy however the veracity of the technique has been questioned on the basis that there is both a spatial and temporal variation in the sr ca ratio of seawater and that kinetic effects such as the calcification rate can affect the sr ca ratio of corals and produce inaccuracies of the order of 2 4 c in the present study a number of cores of the massive hermatypic scleractinian coral porites from the central great barrier reef have been analyzed for sr ca at weekly to monthly resolution results from a 24 year record from myrmidon reef show an overall variation from 22 7 c to 30 4 c the record shows a warming cooling trend with maximum warming centred on the 1986 1987 summer while some bleaching was reported to have occurred at myrmidon reef in 1982 the sr ca record indicates that subsequent summer temperatures were much higher the 4 5 year record from stanley reef shows a maximum sst of 30 c during the 1997 1998 el nino event the calibrations from myrmidon and stanley reefs are in excellent agreement with previously published calibrations from nearby reefs while corals do not calcify in equilibrium with seawater due to physiological control on the uptake of sr and ca into the lattice of coralline aragonite it can be argued that provided only a single genus such as porites sp is used and that the coral is sampled along a major vertical growth axis then the sr ca ratio should vary uniformly with temperature similarly objections based on the spatial and temporal variability of the sr ca activity ratio of seawater can be countered on the basis that in most areas where coral reefs grow there is a uniformity in the sr ca activity ratio and there does not appear to be a change in this ratio over the growth period of the coral evidence from several corals in this study suggest that stress can be a major cause of the breakdown in the sr ca sst relationship thermal stress resulting from either extremely warm or cool temperatures can produce anomalously low sr ca derived ssts as a result of the breakdown of the biological control on sr ca fractionation it is considered that other stresses such as increased nutrients and changes in light intensity can also lead to a breakdown in the sr ca sst relationship two of the main issues affecting the reliability of the sr ca method are the calibration of the sr ca ratio with measured sst and the estimation of tropical last glacial maximum lgm palaeotemperatures instead of producing a constant calibration just about every one published so far is different from the others what is obvious is that for most calibrations while the slope of the calibration equation is similar the intercepts are not while the cause for this variation is still unknown it would appear that corals from different localities around the world are responding to their own particular environment or that certain types of environments exert a control on the corals physiology sr ca derived sst estimates for the lgm and deglaciation of 5 c 6 c cooler than present are at odds with estimates of 2 c 3 c cooling by other climate proxies the apparent lack of reef growth during the lgm suggests that ssts were too cold in many parts of the tropics for reefs to develop this would lend support to the idea that tropical ssts were much cooler than what the climap data suggests

deep sea coral geochemistry implication for the vital effect abstract deep sea corals hold a great potential as a key to important aspects of paleoceanography for at least two reasons 1 they offer temporal high resolution records of deep sea environment because they have growth banding structures 2 and they are well suited for studying vital effects because the deep sea environment does not change over short time scales however the relationship between the chemical composition of deep sea coral skeletons and environmental factors is not well understood in this study the chemical composition of deep sea corals was measured in bulk individuals and along skeletal micro structures among the bulk individuals 18 o value and sr ca ratio show a negative but weak correlation with ambient temperature on the other hand the mg ca ratio has a positive weak correlation with the temperature large variations were found among samples collected from similar temperature the variation is up to 3 8 for 18 o 0 9 mmol mol for sr ca ratios and 0 78 mmol mol for mg ca ratios among samples with ambient average temperature within 1 c this variation may be due to a large vital effect the centers of calcification cocs which were formed at high calcification rate have lower sr ca u ca and higher mg ca ratios than surrounding fasciculi this chemical distribution supports the model that elemental incorporation depends on calcification rate this suggests that calcification rate is a very important factor for the chemical composition in deep sea corals and is one of the most significant mechanisms of the vital effect because of this large vital effect further investigations are essential to use the deep sea coral as a temperature proxy

an integrated field numerical approach to assess slope stability hazards at volcanoes the example of pacaya guatemala pacaya is an active stratovolcano located 30 km south of guatemala city guatemala a large 0 65 km3 sector collapse of the volcano occurred 0 6 1 6 ka b p producing a debris avalanche that traveled 25 km sw of the edifice the current cone has since rebuilt within the scarp of this ancestral collapse the structural setting of the volcano along with two recent smaller volume collapses in 1962 and 2010 suggests gravitational instability of this volcano to assess pacaya s stability and potential for another large lateral collapse of the active cone standard engineering methodologies for studying non volcanic slopes were used to examine the sw flank of the edifice a geomechanical model was developed based on the physical mechanical material properties of pacaya s intact rocks and rock mass characteristics found through field observations and laboratory tests slope stability was analyzed in several scenarios with the limit equilibrium method lem and finite element method fem including static conditions i e under gravity forces only and considering the application of magma pressure and seismic force as triggering mechanisms for slope failure results show that the edifice remains stable under gravity alone however a large scale collapse could be triggered by reasonable ranges of magma pressure 7 7 mpa if constant along a dyke or peak ground acceleration 460 cm s2 results also suggest that a layer of pyroclastics beneath the edifice could have controlled the ancestral sector collapse structural analysis shows that a transtensional stress regime is causing a nw se orientation of aligned features at the surface and may be a controlling mechanism for the direction of a future collapse fem results are concordant with those from lem and reveal that maximum shear strain patterns within the edifice may account for long lava flows erupted from lower vent elevations

impact of biomineralization processes on the mg content of foraminiferal shells a biological perspective the mg ca ratio in foraminiferal shells is widely used as a proxy for paleotemperatures nevertheless it seems that the basic mg content of foraminifera is determined by biological factors as can be concluded from the large inter species and intrashell variability and the frequent deviations from inorganic behavior this paper discusses three possible ways by which foraminifera can control or modify the mg content in their shell 1 involvement of organic matrix in the precipitation process that may alter the partition coefficient of mg in biogenic calcite 2 controlled conversion of transient amorphous phases to calcite and 3 modification of the mg concentration in the parent solution from which the crystals precipitate the first two mechanisms are probably responsible for the precipitation of high mg calcite phases whole shell or sublayers while the third mechanism leads to the formation of low mg calcite phases we propose a model adapted from epithelial cells that allows massive mg2 removal from the biomineralization site this model is especially relevant to the planktonic and deep benthic low mg foraminifera that are frequently used for paleotemperature reconstructions we discuss the possible biological roles of mg in the shell in terms of the calcite polymorph conservation the in vivo chemical stability of the shell the functions of mg as a stabilizer of transient phases and as a controlling agent of the precipitation process several temperature sensitive biological processes that may influence the mg ca ratio of the shell are suggested and a model that combines biogenic and inorganic considerations is presented the model uses mg heterogeneity in the shell together with temperature response biologic and inorganic of biomineralization processes to account for the deviation of planktonic foraminifera from inorganic calcite at equilibrium with seawater

li partitioning in the benthic foraminifera amphistegina lessonii the shallow water benthic foraminifer amphistegina lessonii was grown in seawater of variable li and ca concentration and shell li ca was determined by means of la icpms shell li ca is positively correlated to seawater li ca only when the li concentration of seawater is changed if the seawater ca concentration is changed shell li ca remains constant this indicates that li does not compete with ca for incorporation in the shell of a lessonii a recently proposed calcification model can be applied to divalent cations e g mg and sr which compete for binding sites of ion transporters and positions in the calcite lattice by contrast the transport pathway of monovalent cations such as li is probably diffusion based e g ion channels and monovalent cations do not compete with ca for a position in the calcite lattice here we present a new model for li partitioning into foraminiferal calcite which predicts our experimental results and should also be applicable to other alkali metals

sr ca and mg ca vital effects correlated with skeletal architecture in a scleractinian deep sea coral and the role of rayleigh fractionation deep sea corals are a new tool in paleoceanography with the potential to provide century long records of deep ocean change at sub decadal resolution complicating the reconstruction of past deep sea temperatures mg ca and sr ca paleothermometers in corals are also influenced by non environmental factors termed vital effects to determine the magnitude pattern and mechanism of vital effects we measure detailed collocated sr ca and mg ca ratios using a combination of micromilling and isotope dilution icp ms across skeletal features in recent samples of desmophyllum dianthus a scleractinian coral that grows in the near constant environment of the deep sea sr ca variability across skeletal features is less than 5 2 relative standard deviation and variability of sr ca within the optically dense central band composed of small and irregular aragonite crystals is significantly less than the surrounding skeleton the mean sr ca of the central band 10 6 0 1 mmol mol 2 standard error and that of the surrounding skeleton 10 58 0 09 mmol mol are statistically similar and agree well with the inorganic aragonite sr ca temperature relationship at the temperature of coral growth in the central band mg ca is greater than 3 mmol mol more than twice that of the surrounding skeleton a general result observed in the relative mg ca ratios of d dianthus collected from separate oceanographic locations this large vital effect corresponds to a 10 c signal when calibrated via surface coral mg ca temperature relationships and has the potential to complicate paleoreconstructions outside the central band mg ca ratios increase with decreasing sr ca we explain the correlated behavior of mg ca and sr ca outside the central band by rayleigh fractionation from a closed pool an explanation that has been proposed elsewhere but which is tested in this study by a simple and general relationship we constrain the initial solution and effective partition coefficients for a rayleigh process consistent with our accurate metal ca measurements a process other than rayleigh fractionation influences mg in the central band and our data constrain a number of possible mechanisms for the precipitation of this aragonite understanding the process affecting tracer behavior during coral biomineralization can help us better interpret paleoproxies in biogenic carbonates and lead to an improved deep sea paleothermometer

intrareef variations in li mg and sr ca sea surface temperature proxies in the caribbean reef building coral siderastrea siderea caribbean sea surface temperatures ssts have increased at a rate of 0 2 c per decade since 1971 a rate double that of the mean global change recent investigations of the coral siderastrea siderea on the belize mesoamerican barrier reef system mbrs have demonstrated that warming over the last 30 years has had a detrimental impact on calcification instrumental temperature records in this region are sparse making it necessary to reconstruct longer sst records indirectly through geochemical temperature proxies here we investigate the skeletal sr ca and li mg ratios of s siderea from two distinct reef zones forereef and backreef of the mbrs our field calibrations of s siderea show that li mg and sr ca ratios are well correlated with temperature although both ratios are 3 times more sensitive to temperature change in the forereef than in the backreef these differences suggest that a secondary parameter also influences these sst proxies highlighting the importance for site and species specific sst calibrations application of these paleothermometers to downcore samples reveals highly uncertain reconstructed temperatures in backreef coral but well matched reconstructed temperatures in forereef coral both between sr ca ssts and li mg ssts and in comparison to the hadley centre sea ice and sea surface temperature record reconstructions generated from a combined sr ca and li mg multiproxy calibration improve the precision of these sst reconstructions this result confirms that there are circumstances in which both li mg and sr ca are reliable as stand alone and combined proxies of sea surface temperature however the results also highlight that high precision site specific calibrations remain critical for reconstructing accurate ssts from coral based elemental proxies

lithium in the aragonite skeletons of massive porites corals a new tool to reconstruct tropical sea surface temperatures previous studies have demonstrated the potential for the li content of coral aragonite to record information about environmental conditions but no detailed study of tropical corals exists here we present the li and mg to ca ratios at a bimonthly to monthly resolution over 25 years in two modern porites corals the genus most often used for paleoclimate reconstructions in the tropical indo pacific a strong relationship exists between coral li ca and locally measured sst indicating that coral li ca can be used to reconstruct tropical sst variations however li ca ratios of the skeleton deposited during 1979 1980 do not track local sst well and are anomalously high in places the mg ca ratios of this interval are also anomalously high and we suggest li ca can be used to reconstruct tropical sst only when mg ca data are used to carefully screen for relatively rare biological effects mg li or li mg ratios provide little advantage over li ca ratios except that the slope of the li mg temperature relationship is more similar between the two corals the mg li temperature relationship for the coral that experienced a large temperature range is similar to that found for cold water corals and aragonitic benthic foraminifera in previous studies the comparison with data from other biogenic aragonites suggests the relationship between li mg and water temperature can be described by a single exponential relationship despite this hint at an overarching control it is clear that biological processes strongly influence coral li ca and more calibration work is required before widely applying the proxy

coccolith strontium to calcium ratios in emiliania huxleyi the dependence on seawater strontium and calcium concentrations in recent studies the sr ca ratio of coccolithophore calcite was used as a proxy for past coccolithophore growth and calcification rates since sr and ca concentrations in seawater have not remained constant through time interpretation of sr ca data from the coccolith dominated sedimentary record requires knowledge about the incorporation of seawater sr into coccolith calcite during coccolithogenesis here we show that sr ca of emiliania huxleyi coccoliths is linearly related to seawater sr ca meaning that the sr exchange coefficient does not change with changing seawater sr ca the exchange coefficient for sr in this study 0 39 is close to values presented in the literature and is high compared with values obtained by inorganic precipitation experiments this suggests a strong effect of cell physiology on biogenic calcite precipitation in coccolithophores we present a conceptual model based on the transmembrane transport of sr and ca which explains the offset

cenozoic benthic foraminiferal mg ca and li ca records toward unlocking temperatures and saturation states the sensitivities of benthic foraminiferal mg ca and li ca to bottom water temperature and carbonate saturation state have recently been assessed here we present a new approach that uses paired mg ca and li ca records to calculate simultaneous changes in temperature and saturation state using previously published records we first use this approach to document a cooling of deep ocean waters associated with the establishment of the antarctic ice sheet at the eocene oligocene climate transition we then apply this approach to new records of the middle miocene climate transition from odp site 761 to estimate variations in bottom water temperature and the oxygen isotopic composition of seawater we estimate that the oxygen isotopic composition of seawater varied by 1 between the deglacial extreme of the miocene climatic optimum and the glacial maximum following the middle miocene climate transition indicating large amplitude variations in ice volume however the longer term change between 15 3 and 12 5 ma is marked by a 1 c cooling of deep waters and an increase in the oxygen isotopic composition of seawater of 0 6 we find that bottom water saturation state increased in the lead up to the middle miocene climate transition and decreased shortly after this supports decreasing pco2 as a driver for global cooling and ice sheet expansion in agreement with existing boron isotope and leaf stomatal index co2 records but in contrast to the published alkenone co2 records

li sr mg and na in foraminiferal calcite shells from laboratory culture sediment traps and sediment cores abstract constant temperature laboratory culture experiments of the planktonic foraminiferal species globigerinoides sacculifer brady suggest that the ratios of li and sr to ca in the shells are a function of these ratios in the culture solutions mg ca and na ca in the shells did not vary with changes of these ratios in the culture solution these are the first direct determinations of the relationship between foraminiferal shell chemistry and solution composition the possibility of temperature dependence for the minor elemental composition of foraminiferal shells was also investigated in the laboratory and by analysis of several planktonic and one benthic foraminiferal species from sediment trap and sediment core samples the sr ca mg ca and na ca ratios in the natural samples roughly correlate with calcification temperature whereas differences in the li ca ratios are small and not systematically related to temperature however laboratory culture experiments at 20 c and 30 c showed no variation in the li ca sr ca mg ca and na ca ratios with calcification temperature for the planktonic foraminifera g sacculifer and orbulina universa therefore observed differences in the sr ca mg ca and na ca ratios for the sediment trap and core foraminiferal samples cannot be ascribed to direct effects of calcification temperature but may be due to some other environmental factor which is correlated with temperature

seawater transport during coral biomineralization cation transport during skeletal growth is a key process controlling metal calcium me ca paleoproxy behavior in coral to characterize this transport cultured corals were transferred into seawater enriched in the rare earth element tb 3 as well as stable isotopes of calcium strontium and barium subsequent nanosims ion images of each coral skeleton were used to follow uptake dynamics these images show a continuous region corresponding to new growth that is homogeneously enriched in each tracer isotope ratio profiles across the new growth boundary transition rapidly from natural abundance ratios to a ratio matching the enriched culture solution the location of this transition is the same for each element within analytical resolution the synchronous incorporation of all these cations including the dissimilar ion terbium which has no known biological function in coral suggests that 1 there is cation exchange between seawater and the calcifying fluid and 2 these elements are influenced by similar transport mechanisms consistent with direct and rapid seawater transport to the site of calcification measured using isotope ratio profiles seawater transport rates differ from place to place on the growing coral skeleton with calcifying fluid turnover times from 30 min to 5 7 h despite these differences all the elements measured in this study show the same transport dynamics at each location using an analytical geochemical model of biomineralization that includes direct seawater transport we constrain the role of active calcium pumping during calcification and we show that the balance between seawater transport and precipitation can explain observed me ca variability in deep sea coral

sector collapse of the sw flank of volcan de colima mexico the 3600 yr bp la lumbre los ganchos debris avalanche and associated debris flows abstract some 3600 years ago the sw flank of volcan de colima collapsed generating a debris avalanche that travelled 25 km to the armeria river and stopped against the cerro grande limestone escarpment the debris avalanche deposit covers an area of 48 km2 has an average thickness of 35 m and a volume of 1 7 km3 with an h l ratio of 0 13 along the la lumbre ravine the deposit forms a series of flat terraces up to 65 m thick a pyroclastic flow deposit overlies the debris avalanche deposit suggesting that the colima collapse was accompanied by a magmatic component the debris avalanche deposit dammed the armeria river forming a temporary lake that accumulated a water volume of 0 19 km3 the subsequent breaking of the dam formed a debris flow that travelled at least 20 km along the armeria river emplacing 15 70 m thick deposits the debris flow deposits cover a surface of 6 4 km2 and have a volume of 0 2 km3 the avalanche deposit contains fragments of carbonized wood that where dated at 3600 120 yr bp by komorowski et al 1997 this deposit underlies a younger debris avalanche 2505 45 yr bp and a debris flow deposit with pottery shards and charcoal dated at 1940 90 yr bp these pottery shards likely related to the capacha people 820 300 yr bc indicating that the region has been inhabited during the last 3000 years a future collapse of volcan de colima in the same direction may affect several towns for a total population of circa 40 000

temperature and carbonate ion effects on mg ca and sr ca ratios in benthic foraminifera aragonitic species hoeglundina elegans received 16 march 2005 revised 20 june 2005 accepted 3 november 2005 published 21 february 2006 1 core top samples from atlantic little bahama banks lbb and pacific hawaii and indonesia depth transects have been analyzed in order to assess the influence of bottom water temperature bwt and aragonite saturation levels on mg ca and sr ca ratios in the aragonitic benthic foraminifer hoeglundina elegans both the mg ca and sr ca ratios in h elegans tests show a general decrease with increasing water depth although at each site the decreasing trends are consistent with the in situ temperature profile mg ca and sr ca ratios in lbb are substantially higher than in indonesia and hawaii at comparable water depths with a greater difference observed with increasing water depth because we find no significant difference between results obtained on live and dead specimens we propose that these differences are due to primary effects on the metal uptake during test formation evaluation of the water column properties at each site suggests that in situ co3 ion concentrations play an important role in determining the h elegans mg ca and sr ca ratios the co3 ion effect is limited however only to aragonite saturation levels dco3 aragonite below 15 mmol kg 1 above this level temperature exerts a dominant effect accordingly we propose that mg ca and sr ca in h elegans tests can be used to reconstruct thermocline temperatures only in waters oversaturated with respect to the mineral aragonite using the following relationships mg ca 0 034 0 002 bwt 0 96 0 03 and sr ca 0 060 0 002 bwt 1 53 0 03 for dco3 aragonite 1 5mmol kg 1 the standard error associated with these equations is about 1 1 c reconstruction of deeper water temperatures is complicated because in undersaturated waters changes in mg ca and sr ca ratios reflect a combination of changes in co3 and bwt overall we find that sr ca rather than mg ca in h elegans may be a more accurate proxy for reconstructing paleotemperatures

coral li mg thermometry caveats and constraints abstract the coral li mg temperature proxy is revisited through an in depth trace element analysis of scleractinians collected live from tropical to polar environments the dataset consists of li ca mg ca sr ca and li mg ratios from 64 coral specimens belonging to 8 different taxa including both reef building zooxanthellate and cold water non zooxanthellate species from a wide range of water temperature 1 to 29 5 c salinity 34 71 to 38 61 and depth 3 to 670 m our results showed that the reliability of the li mg temperature proxy is strongly limited by the organic matter associated with the coral skeleton which is most evident within the green bands observed in tropical corals organic rich bands can double the mg content otherwise present in the skeleton which may ultimately lead to a temperature overestimation exceeding 15 c we found that this bias can be overcome by the treatment of coral skeletons with a specific oxidizing cleaning protocol we also detected the presence of calcite deposits within the aragonite skeleton of some antarctic living coral specimens which strongly affects the robustness of the li mg proxy given its temperature sensitivity of 1 5 c 1 calcite therefore to obtain reliable reconstructions a correction needs to be applied when organic matter and or calcite contamination is present which requires the scrupulous assessment of the integrity of the aragonite prior to geochemical analyses given that some species entrap more organic matter than others and that some are more prone to calcite contamination a taxon related effect is apparent here we show that the tropical species porites spp pseudodiploria strigosa and orbicella annularis and the cold water species madrepora oculata caryophyllia antarctica and flabellum impensum are all suitable candidates for reconstructing seawater temperatures the integrated results across a wide temperature range from extreme cold to tropical shallow waters yield an overall precision for the li mg temperature proxy of 1 0 c as quantified by the standard error of estimates if calculated from the 95 prediction intervals the uncertainty of the temperature estimates is 0 9 c at 1 c 1 5 c at 12 c and 2 6 c at 25 c however the uncertainty for the tropical corals e g porites can be reduced to 0 6 c if a li mg and sr ca multi regression approach is applied

debris avalanche deposits of the milo lahar sequence and the opening of the valle del bove on etna volcano italy previously undescribed debris avalanche deposits occur in two locations downslope from the open end of the valle del bove these outcrops comprise unstratified ungraded deposits of metre scale lava blocks in a matrix of weathered and fractured lava clasts the avalanche deposits are unconformably overlain by matrix to clast supported conglomerates representing debris flow and interbedded fluvial deposits that constitute most of the milo lahar sequence we present evidence that the milo lahar sequence which crops out just at the exit of the valle del bove formed during the opening and enlargement of this depression the presence of the avalanche deposits at the base of the milo lahar sequence indicates that catastrophic landslides were involved in the formation of the valle del bove the composition of lavas in the debris avalanche deposits is similar to that of most of the ellittico volcanic sequence exposed along the northern wall of the valle del bove radiocarbon dates of 8400 and 5300 years bp from the base and top respectively of the debris flow sequence indicate that the milo lahars are correlative with the exposed part of the chiancone deposit the basal lahars of the chiancone which contain lava blocks whose compositions partially overlap that of blocks in the avalanche deposits may have formed by water concentration in the distal end of the avalanche causing transformation to debris or alternatively by reworking of the avalanche deposit

calcium isotope fractionation in calcite and aragonite abstract calcium isotope fractionation was measured on skeletal aragonite and calcite from different marine biota and on inorganic calcite precipitation temperatures ranged from 0 to 28 c calcium isotope fractionation shows a temperature dependence in accordance with previous observations 1000 ln cc 1 4 0 021 t c for calcite and 1000 ln ar 1 9 0 017 t c for aragonite within uncertainty the temperature slopes are identical for the two polymorphs however at all temperatures calcium isotopes are more fractionated in aragonite than in calcite the offset in 44 40 ca is about 0 6 the underlying mechanism for this offset may be related to the different coordination numbers and bond strengths of the calcium ions in calcite and aragonite crystals or to different ca reaction behavior at the solid liquid interface recently the observed temperature dependence of the ca isotope fractionation was explained quantitatively by the temperature control on precipitation rates of calcium carbonates in an experimental setting lemarchand et al 2004 we show that this mechanism can in principle also be applied to caco 3 precipitation in natural environments in normal marine settings following this model ca isotope fractionation in marine ca carbonates is primarily controlled by precipitation rates on the other hand the larger ca isotope fractionation of aragonite compared to calcite can not be explained by different precipitation rates the rate control model of ca isotope fractionation predicts a strong dependence of the ca isotopic composition of carbonates on ambient co 3 2 concentration while this model is in general accordance with our observations in marine carbonates cultured specimens of the planktic foraminifer orbulina universa show no dependence of ca isotope fractionation on the ambient co 3 2 concentration the latter observation implies that the carbonate chemistry in the calcifying vesicles of the foraminifer is independent from the ambient carbonate ion concentration of the surrounding water

tsunamis generated by eruptions from mount st augustine volcano alaska during an eruption of the alaskan volcano mount st augustine in the spring of 1986 there was concern about the possibility that a tsunami might be generated by the collapse of a portion of the volcano into the shallow water of cook inlet a similar edifice collapse of the volcano and ensuing sea wave occurred during an eruption in 1883 other sea waves resulting in great loss of life and property have been generated by the eruption of coastal volcanos around the world although mount st augustine remained intact during this eruptive cycle a possible recurrence of the 1883 events spurred a numerical simulation of the 1883 sea wave this simulation which yielded a forecast of potential wave heights and travel times was based on a method that could be applied generally to other coastal volcanos

refining trace metal temperature proxies in cold water scleractinian and stylasterid corals abstract the li mg sr ca and oxygen isotopic 18 o compositions of many marine biogenic carbonates are sensitive to seawater temperature corals as cosmopolitan marine taxa with carbonate skeletons that can be precisely dated represent ideal hosts for these geochemical proxies however efforts to calibrate and refine temperature proxies in cold water corals 18 o and carbon isotope 13 c data from live collected specimens of aragonitic scleractinian corals balanophyllia caryophyllia desmophyllum enallopsammia flabellum lophelia and vaughanella both aragonitic and high mg calcitic stylasterid genera stylaster and errina and shallow water high mg calcite crustose coralline algae lithophyllum hydrolithon and neogoniolithon we interpret these data in conjunction with results from previously explored taxa including aragonitic zooxanthellate scleractinia and foraminifera and high mg calcite octocorals we show that li mg ratios covary most strongly with seawater temperature both for aragonitic and high mg calcitic taxa making for reliable and universal seawater temperature proxies combining all of our biogenic aragonitic li mg data with previous calibration efforts we report a refined relationship to temperature li mgall aragonite 5 42 exp 0 050 t c r 2 0 97 this calibration now permits paleo temperature reconstruction to better than 3 4 c 95 prediction intervals across biogenic aragonites regardless of taxon from 0 to 30 c for taxa in this study aragonitic stylasterid li mg offers the most robust temperature proxy li mgstylasterid arag 5 64 exp 0 046 t c r 2 0 95 with a reproducibility of 2 3 c for the first time we show that high mg calcites have a similar exponential relationship with temperature but with a lower intercept value li mg 0 63 exp 0 050 t c r 2 0 92 this calibration opens the possibility of temperature reconstruction using high mg calcite corals and coralline algae the commonality in the relationship between li mg and temperature transcends phylogeny and suggests a similar abiogenic trace metal incorporation mechanism

glacial deep ocean sequestration of co2 driven by the eastern equatorial pacific biologic pump abstract the potential influence of low latitude ocean primary productivity on glacial atmospheric carbon dioxide levels has proven challenging to deduce using mass accumulation rates mars of biogenic particulates in deep sea sediment cores benthic foraminiferal b ca serves as a proxy for past seawater calcite saturation state and thereby provides a fresh perspective on this outstanding paleoceanographic problem here we employ cibicidoides wuellerstorfi b ca in the panama basin region of the eastern equatorial pacific eep to investigate the nature of deep tropical pacific carbon storage over the past 50 ka bp we present evidence for persistently lower deep panama basin calcite saturation state reflecting an increase in total carbon dioxide storage during the last ice age relative to the holocene these results reflect the modification of inflowing deep waters by overlying export productivity and support the concept of an invigorated glacial eep soft tissue pump possibly driven by oceanic nutrient iron and silica redistribution benthic cibicidoides spp carbon 13 is consistent with this conclusion by exhibiting substantially lighter values during glacial time reflecting the accumulation of metabolic carbon dioxide in the deep tropical pacific counterintuitively downcore application of the globorotalia menardii calcite fragmentation index mfi reveals enhanced glacial sedimentary calcite preservation in the panama basin together these results point towards a systematic decoupling of bottom water chemistry from biogenic burial fluxes the crux of the aforementioned traditional paleoproductivity problem

a biomineralization model for the incorporation of trace elements into foraminiferal calcium carbonate measurements of srca of benthic foraminifera show a linear decrease with water depth which is superimposed upon significant variability identified by analyses of individual foraminifera new data for cdca support previous work in defining a contrast between waters shallower and deeper than 2500 m measured element partition coefficients in foraminiferal calcium carbonate relative to sea water d have been described by means of a one box model in which elements are extracted by rayleigh distillation from a biomineralization reservoir that serves for calcification with a constant fractionation factor such that d 1 f 1 f where f is the proportion of ca remaining after precipitation a modification to the model recognises differences in element speciation the model is consistent with differences between dsr dba and dcd in benthic but not planktonic foraminifera depth variations in d for sr and ba are consistent with the model as are differences in depth variation of dcd in calcitic and aragonitic benthic foraminifera the shallower depth variations may reflect increasing calcification rates with increasing water depth to an optimum of about 2500 m observations of unusually lower dcd for some deep waters not accompanied by similar dsr or dba may be because of dissolution or a calcification response to a lower carbonate saturation state

characterization of debris avalanche deposits in japan abstract seventy one debris avalanche deposits are identified from 52 japanese quaternary volcanoes the structures of these volcanoes are mostly stratovolcanoes and lava domes no avalanche deposit is found in calderas pyroclastic cones or maar volcanoes debris avalanche deposits are found in 18 of all quaternary volcanoes or 25 of quaternary stratovolcanoes and lava domes the ratio rises to 49 when considering only active stratovolcanoes and lava domes at least five debris avalanche deposits have formed since 9th century the maximum height difference of sliding h for each debris avalanche ranges from 200 to 2400 meters and the maximum runout distance of sliding l ranges from 1 6 to 32 km the ratio h l ranges from 0 2 to 0 06 and becomes smaller in larger debris avalanches they are more mobile than landslides in non volcanic areas volume is within a range of 0 03 and 9 km 3 there is no relation between the direction of sliding and the regional horizontal compressional stress axis at the site of a volcano two dimensional computer simulations of avalanches using a simplified physical model are made the maximum velocity is mainly controlled by the length of steep slope

characterisation of a volcanic residual soil and its implications for large landslide phenomena application to tenerife canary islands large landslides are common processes during the evolution of volcanoes and individual events can exceed several cubic kilometres in volume volcanic slope failures are a significant risk for the neighbouring population due to their huge volumes and great runout distances around the canary archipelago a total of seventeen deposits of large landslides have been found and on tenerife seven large landslides have affected the subaerial and submarine morphology during the last 6 ma however the causes of such mass movements are still poorly understood this work analyses the events around the canary islands and focuses on the ones that occurred on tenerife in order to obtain new insights into the mechanisms of large volcanic landslides the study is divided into a first part that includes site investigations examining the general features favouring large scale failures at volcanoes the second part describes the laboratory tests used to analyse a residual soil that may be the potential slip surface of the slides on tenerife the site investigation revealed that regional tectonics and the climate have a significant influence on the spatial distribution of the landslides moreover morphological and geological features such as deep fluvial canyons a high coastal cliff and persistent dike intrusion may favour the initiation of slope failure a typical residual soil sample from the lateral scarp of the la orotava amphitheatre on tenerife was studied by carrying out standard laboratory tests the microstructure was analysed using environmental scanning electron microscopy and a particular bonding was found this bonding was also detected by the geotechnical tests consolidation tests and direct shear tests revealed that the mechanical behaviour of the residual soil changes greatly if the bonding of the soil is broken the bonded structure generally fails when the effective normal stress surpasses the yield strength of the bonding in the case of large volcanic landslides with thicknesses up to several hundred meters the high overburden easily exceeds this yield strength and generates a broken bonding therefore volcanic residual soils such as the one analysed in this study are perfect candidates for the potential failure surfaces of large volcanic landslides referring to the la orotava events we assume that residual soil layers and morphological geological and climatic features reduced the slope stability to critical conditions whereas a strong earthquake associated with a caldera collapse episode may have finally triggered the landslide the results obtained indicate that the residual soils play an important role in affecting the stability of volcano slopes and their destabilising influence significantly favours large scale sliding we suggest that the results obtained from this study can be applied to other locations since volcanic residual soils are common in volcanic areas