modification and preservation of environmental signals in speleothems speleothems are primarily studied in order to generate archives of climatic change and results have led to significant advances in identifying and dating major shifts in the climate system however the climatological meaning of many speleothem records cannot be interpreted unequivocally this is particularly so for more subtle shifts and shorter time periods but the use of multiple proxies and improving understanding of formation mechanisms offers a clear way forward

high resolution secondary ionisation mass spectrometry sims δ18o analyses of hulu cave speleothem at the time of heinrich event 1 abstract the suitability of in situ secondary ionisation mass spectrometry sims techniques for measuring o isotopes in speleothems is critically examined by applying this technique to a 500 year interval of the well known hulu cave record wang y j cheng h edwards r l an z s wu j y shen c c dorale j a 2001 a high resolution absolute dated late pleistocene monsoon record from hulu cave china science 294 2345 2348 this interval includes a large abrupt 2 shift in 18o at 16 07 ka which may correlate to heinrich event i h1 the high resolution sims method provides annual to near annual 18o data thereby increasing the temporal resolution of the previously published hulu cave isotopic data by approximately tenfold sims 18o data reveal that 75 of the abrupt isotopic shift at 16 07 ka occurred in just 1 to 2 years and the full 2 occurs over 6 years compared with an upper limit of 20 years as previously determined by conventional methods employing micro cutting acid digestion and co2 gas source mass spectrometry methods sims 18o data also reveal numerous high amplitude 1 3 high frequency

oxygen and hydrogen isotopic variations between adjacent drips in three caves at increasing elevation in a temperate coastal rainforest vancouver island canada abstract the interpretation of speleothem paleoenvironmental records requires understanding of spatial temporal variations in vadose drip water chemistry and isotopic composition this study reports on intra and inter cave differences in d 18o and electrical conductivity using 18 monthly water samples from three adjacent drips all drips showed isotopic seasonal signals despite varied patterns of drip hydrology there was overlap in isotopic ranges at 1 sd between all three caves in contrast with the expected 18o depletion of 0 15 to 0 5 100 m of ascent observed in standard precipitation the isotopic seasonality was approximated with sine curves and compared to a gnip data set from victoria 300 km to the south the d and 18o drip isotopes lagged the victoria record by 155 26 days and 165 50 days respectively the longest lag was at the slowest drip sea level while the shortest lag 87 days for 18o 550 m asl implies a short residence time paradoxically from the drip with the highest mean electrical conductivity vadose residence time was less than one climatic year reflecting a combination of negligible matrix porosity in the host rock and super humid climatic conditions beneath the epikarst drip hydrology was evidently by simple piston flow phase shifted drip isotope records showed excellent agreement with sea level mean monthly air temperatures at the tahsis meteorological station over the study period the d and 18o drip amplitudes were damped on average 74 and 73 respectively compared to the victoria data the drips at 740 m asl are tightly aligned to the global mean meteoric water line gmwl and 18o depleted the drips at 550 m asl and at sea level plot along the gmwl or between it and the victoria lmwl with the exception of the slowest drip sea level which displays some seasonal evaporitic enrichment the findings quantify substantial intra and inter cave variation of d and 18o in drips having a wide range of drip type and volume of flow sufficient to mute the altitudinal isotopic lapse rate in this local coastal rainforest environment

oxygen and hydrogen isotopes in the hydrologic cycle changes of the isotopic composition of water within the water cycle provide a recognizable signature relating such water to the different phases of the cycle the isotope fractionations that accompany the evaporation from the ocean and other surface waters and the reverse process of rain formation account for the most notable changes as a result meteoric waters are depleted in the heavy isotopic species of h and o relative to ocean waters whereas waters in evaporative systems such as lakes plants and soilwaters are relatively enriched during the passage through the aquifers the isotope composition of water is essentially a conservative property at ambient temperatures but at elevated temperatures interaction with the rock matrix may perturb the isotope composition these changes of the isotope composition in atmospheric waters surface water soil and groundwaters as well as in the biosphere are applied in the characterization of hydrological system as well as indicators of paleo climatological conditions in proxy materials in climatic archives such as ice lake sediments or organic materials

seasonal isotopic variability of precipitation and cave drip water at indian oven cave new york a major assumption in palaeoclimatic studies using speleothems is that cave seepage waters are homogenized as they pass through the bedrock so that they record the average annual isotopic signal of precipitation a year long study during 2001 02 was conducted at indian oven cave in eastern new york state usa to investigate how cave seepage water isotopic signals relate to those of precipitation samples were collected biweekly and analysed for stable isotopes of oxygen and hydrogen our study shows that for this cave homogenization did not occur as seepage waters had the same seasonal variability as precipitation however mean seepage water isotopic values were very close to those of the mean values for precipitation rapid flow through times of seepage water show that the speleothems can record climate conditions above the cave contemporaneously at one location flow ceased during the winter therefore isotopes measured in cave drip waters reflected only the enriched summer isotopes under certain circumstances the analysis of calcite sampled from those drip waters may then lead to a false conclusion of a warming during that period instead of the fact that it was merely a drier winter period copyright 2005 john wiley sons ltd

in situ stable isotopic evidence for protracted and complex carbonate cementation in a petroleum reservoir north coles levee san joaquin basin california u s a abstract knowledge of the evolution of carbonate cementation in hydrocarbon reservoirs is key to understanding the history of fluid flow during petroleum accumulation the stevens sands is a sequence of marine shales and deep sea fan sands that was deposited within the miocene monterey formation in the south central part of the san joaquin basin california during the upper miocene 10 6 ma rapid high precision in situ oxygen and carbon isotopic analyses of carbonate phases using the ion microprobe operated in multi collection mode in conjunction with electron microprobe analyses indicate that carbonate cement zones within the stevens sands at north coles levee ncl have had a complex and protracted fluid history three main generations of carbonate cement were identified the relative timing of carbonate cement precipitation within the stevens sands at ncl was estimated using the thermal and burial history of the san joaquin basin in situ oxygen isotope data and cementation temperatures derived from equilibrium oxygen isotope fractionation factors for calcite water and dolomite water precipitation of these cement zones began soon after sediment deposition 7 ma and is ongoing early dolomite was precipitated at a temperature of 10 c near the sediment water interface and soon after sediment deposition calcite cements which are the most abundant variety precipitated semicontinuously between 4 ma and 5 ma at temperatures between 50 c and 65 c and depths of 800 m to 1300 m fe dolomite which is paragenetically late appears to have precipitated at temperatures near 100 c in response to pore pressure reduction which accompanied exploitation of the gas cap within the last 35 years carbon in these cements was likely derived from several sources including marine maturing hydrocarbons and a zone of methanogenesis

late quaternary paleoclimate in the eastern mediterranean region from stable isotope analysis of speleothems at soreq cave israel abstract the eastern mediterranean continental paleoclimate during the past 25 000 years was determined by a high resolution petrographic stable isotopic and age study of speleothems from soreq cave israel 18o 13c trends indicate that all speleothems older than 7000 yr formed under conditions that differ from those of today the period from 25 000 to 17 000 yr b p was characterized by the highest 18o and 13c values which indicate deposition at temperatures of 12 16 c annual rainfall of 300 450 mm and vegetation typical of a mixed c3 c4type from 17 000 to 10 000 yr b p deglaciation in northern europe 18o values dropped progressively correlative with warming 2 3 c and a gradual increase in precipitation a simultaneous decrease in 13c gives a range expected for c3 type vegetation this period also shows significant 18o and 13c spikes which are correlatable with global events e g heinrich events and the younger dryas stade the speleothems that grew between 10 000 and 7000 yr b p have a unique petrography showing irregular thin laminae of various colors and much detritus they have the lowest 18o corresponding to 1000 mm rain coupled with the highest 13c caused by flooding events which stripped the soil cover from 7000 to 1000 yr b p conditions became closer to those of today this study demonstrates that global events which were recognized in northern europe and north africa are also evident in the eastern mediterranean and are reflected principally by large changes in the rainfall rate

a high resolution record of holocene climate change in speleothem calcite from cold water cave northeast iowa high precision uranium thorium mass spectrometric chronology and 18o 13c isotopic analysis of speleothem calcite from cold water cave in northeast iowa have been used to chart mid holocene climate change significant shifts in 18o and 13c isotopic values coincide with well documented holocene vegetation changes temperature estimates based on 18o 16o ratios suggest that the climate warmed rapidly by about 3 c at 5900 years before present and then cooled by 4 c at 3600 years before present initiation of a gradual increase in 13c at 5900 years before present suggests that turnover of the forest soil biomass was slow and that equilibrium with prairie vegetation was not attained by 3600 years before present

pleistocene glaciations of central asia results from 10be surface exposure ages of erratic boulders from the pamir tajikistan and the alay turkestan range kyrgyzstan abstract we have determined the timing of glaciations in the pamir tajikistan and the alay turkestan range kyrgyzstan using 10be surface exposure dating glacial advances in the area have occurred 93 136 60 80 40 55 27 25 22 20 19 17 16 15 15 13 and 11 9 cal ka bp all late pleistocene glaciers in the pamir and the alay turkestan ranges have been valley glaciers except for the most extended glaciers on the pamir plateau which have formed local piedmont glaciations in the eastern pamir these are characterized by ela depressions of 370 380 m thar 0 5 in the turkestan range and alay range ela depressions at the same time were 750 and 600 m respectively late pleistocene glacier advances all over western high asia were contemporaneous with climatic cold phases rather than monsoonal maxima their maximum extent and that of the western hemisphere ice sheets were asynchronous due to increasing aridity in the region over the course of the last glacial late pleistocene climate in central asia seems to have been influenced by the interplay of the westerly circulation and the siberian anticyclone some indirect monsoonal influence in the eastern pamir may be responsible for the existence of some of the lateglacial moraine stages in this area high altitude glaciers seem to have reached their maximum extent earlier mis 5 4 than low altitude glaciers first half of mis 3 possibly due to prolonged glacial aridity imparting with moisture advection onto high altitude sites inducing glacial retreat but prolonged cold during the same time imparting with glacier ablation at lower altitude sites inducing glacial advance

rapid uplift of the altiplano revealed through 13c 18o bonds in paleosol carbonates the elevation of earth s surface is among the most difficult environmental variables to reconstruct from the geological record here we describe an approach to paleoaltimetry based on independent and simultaneous determinations of soil temperatures and the oxygen isotope compositions of soil waters constrained by measurements of abundances of 13 c 18 o bonds in soil carbonates we use this approach to show that the altiplano plateau in the bolivian andes rose at an average rate of 1 03 0 12 millimeters per year between 10 3 and 6 7 million years ago this rate is consistent with the removal of dense lower crust and or lithospheric mantle as the cause of elevation gain

space geodetic constraints on glacial isostatic adjustment in fennoscandia analysis of global positioning system gps data demonstrates that ongoing three dimensional crustal deformation in fennoscandia is dominated by glacial isostatic adjustment our comparison of these gps observations with numerical predictions yields an earth model that satis es independent geologic constraints and bounds both the average viscosity in the upper mantle 5 x 10 20 to 1 x 10 21 pascal seconds and the elastic thickness of the lithosphere 90 to 170 kilometers we combined gps derived radial motions with fennoscandian tide gauge records to estimate a regional sea surface rise of 2 1 0 3 mm year furthermore ongoing horizontal tectonic motions greater than 1 mm year are ruled out on the basis of the gps derived three dimensional crustal velocity field

stable isotope variation in tooth enamel from neogene hippopotamids monitor of meso and global climate and rift dynamics on the albertine rift uganda the neogene was a period of long term global cooling and increasing climatic variability variations in african asian monsoon intensity over the last 7 ma have been deduced from patterns of eolian dust export into the indian ocean and mediterranean sea as well as from lake level records in the east african rift system ears however lake systems not only depend on rainfall patterns but also on the size and physiography of river catchment areas this study is based on stable isotope proxy data 18o 16o 13c 12c from tooth enamel of hippopotamids mammalia and aims in unravelling long term climate and watershed dynamics that control the evolution of palaeolake systems in the western branch of the ears lake albert uganda during the late neogene 7 5 ma to recent having no dietary preferences with respect to wooded c3 versus grassland c4 vegetation these territorial water dependant mammals are particularly useful for palaeoclimate analyses as inhabitants of lakes and rivers hippopotamid tooth enamel isotope data document mesoclimates of topographic depressions such as the rift valleys and therefore changes in relative valley depth instead of exclusively global climate changes consequently we ascribe a synchronous maximum in 18o 16o and 13c 12c composition of hippopotamid enamel centred around 1 5 2 5 ma to maximum aridity and or maximum hydrological isolation of the rift floor from rift external river catchment areas in response to the combined effects of rift shoulder uplift and subsidence of the rift valley floor structural rearrangements by 2 5 ma within the northern segment of the albertine rift are well constrained by reversals in river flow cannibalisation of catchments biogeographic turnover and uplift of the rwenzori horst however a growing rain shadow is not obvious in 18o 16o signatures of the hippopotamid teeth of the albertine rift according to our interpretation this is the result of the overriding effect of evaporation on 18o 16o responding to aridification of the basin floor by a valley air circulation system through relative deepening of the valley on the other hand a synchronous arid pulse is not so clearly recorded in palaeosol data and mammalian fauna of the eastern branch of the ears this discrepancy indicates that rift mesoclimates may represent an underestimated aspect in previous palaeoclimate reconstructions from rift valley data and represent a clear limitation to attempts at global climate reconstructions the results of this study also suggest that using 18o 16o data as a proxy to rain shadow evolution must take into account relative basin subsidence to properly document mountain range uplift

high times on the tibetan plateau paleoelevation of the thakkhola graben nepal east west extension in the tibetan plateau is generally assumed to have resulted from gravitational collapse following thickening and uplift on the basis of this assumption several studies have dated east west extensional structures to determine when the plateau attained its current high elevation however independent estimates of elevation are needed to determine whether extension occurred before during or after the plateau achieved its current elevation because the isotopic composition of meteoric water decreases with increasing elevation significant change in local elevation throughout the thakkhola graben depositional history should be recorded by change in 18 o values of fluvial and lacustrine carbonates the 18 o values of 16 to 23 of thakkhola graben carbonates reflect meteoric water values similar to modern values and suggest that the southern tibetan plateau attained its current elevation prior to eastwest extension initiation of thakkhola graben extension is constrained between 10 and 11 ma based on magnetostratigraphy of the older tetang formation the 13 c values of soil carbonates suggest an age younger than 8 ma for the base of the thakkhola formation

ultra deep oxidation and exotic copper formation at the late pliocene boyongan and bayugo porphyry copper gold deposits surigao philippines geology mineralogy paleoaltimetry and their implications for geologic physiographic and tectonic controls the boyongan and bayugo porphyry copper gold deposits are part of an emerging belt of intrusion centered gold rich deposits in the surigao district of northeast mindanao philippines exhumation and weathering of these late pliocene age deposits has led to the development of the world s deepest known porphyry oxidation profile at boyongan 600 m and yet only a modest 30 70 m oxidation profile at adjacent bayugo debris flows volcanic rocks and fluviolacustrine sediments accumulating in the actively extending mainit graben subsequently covered the deposits and preserved the supergene profiles at boyongan and bayugo there is a vertical transition from shallower supergene copper oxide minerals malachite azurite cuprite to deeper sulfide stable assemblages chalcocite hypogene sulfides this transition provides a time integrated proxy for the position of the water table at the base of the saturated zone during supergene oxidation contours of the elevation of the paleopotentiometric surface based on this mineralogical transition show that the thickest portions of the unsaturated zone coincided with a silt sand matrix diatreme breccia complex at boyongan within the breccia complex the thickness of the unsaturated zone approached 600 m whereas outside the breccia complex e g at bayugo the thickness averaged 50 m contours of the paleopotentiometric surface suggest that during weathering groundwater flowed into the breccia complex from the north south and east and exited along a high permeability zone to the west the high relief 550 m on the elevation of the paleopotentiometric surface is consistent with an environment of high topographic relief and the outflow zone to the west of the breccia complex probably reflects proximity to a steep scarp intersecting the western breccia complex margin stable isotope paleoaltimetry has enabled estimation of the elevation of the land surface which further constrains the physiographic setting during supergene oxidation isotopic measurements of oxygen in supergene kaolinite from boyongan suggest that local paleometeoric water involved in weathering had a 18o composition of approximately 5 7 per mil at the latitude of the southern philippines this value corresponds to pleistocene rain water condensing at elevations between 750 and 1 050 m above contemporary sea level providing a maximum estimate for the surface elevation during weathering of the porphyry systems physiographic reconstructions suggest that the deep oxidation profile at boyongan formed in an environment of high topographic relief immediately east of a prominent 550 m escarpment the high permeability contrast between the breccia complex and the surrounding wall rocks coupled with the proximity of the breccia complex to the escarpment led to a depressed groundwater table and a vertically extensive unsaturated zone in the immediate vicinity of boyongan this thick vadose zone and the low hypogene pyrite copper sulfide ratios 0 6 at boyongan promoted in situ oxidation of copper sulfides with only modest 200 m supergene remobilization of copper in contrast higher hypogene pyrite chalcopyrite ratios 2 3 at bayugo led to greater acid production during weathering and more complete leaching of copper above the base of oxidation this process promoted significant 600 m lateral dispersion of copper down the paleohydraulic gradient into the diatreme breccia comple ultimately leading to the formation of an exotic copper deposit

timing and hydrological conditions of sapropel events in the eastern mediterranean as evident from speleothems soreq cave israel this paper explores the connection between the timing of sapropel events in the eastern mediterranean sea and the time of low 18o events in speleothems of the soreq cave israel a new well dated 18o and 13c profile of the soreq cave speleothems for the last 140 kyr reveals five prominent low 18o events dated at 124 to 119 kyr with the main peak at 122 kyr event v 108 to 100 kyr with peaks at 107 and 102 kyr event iv 85 to 79 kyr with peak at 80 kyr event iii 55 to 52 kyr with a peak at 54 kyr event ii and 8 5 to 7 kyr with peaks at 8 5 and 7 kyr event i these events are characteristic of period of enhanced rainfall in the eastern mediterranean area particularly so for events v and i where the marked decrease in 18o and the correspondingly marked increase in 13c indicate very wet conditions the chronology of the low 18o events v iv iii and i match the ages estimated for the formation of sapropels s5 s4 s3 and s1 which are also associated with high hydrological activity thus it is suggested that the low 18o events in the soreq cave speleothems constrain the maximum duration of the sapropel formation pollen data from the sapropel layers and the isotopic pattern of the speleothems indicate that sapropels s5 and s1 were deposited during very wet periods when there were major decrease in the sea surface salinity coupled with frost free winters and drought free summers sapropels s4 and s3 were formed during periods of increased precipitation but ones in which the general climate was mediterranean semi arid

the transfer of seasonal isotopic variability between precipitation and drip water at eight caves in the monsoon regions of china abstract this study presents new stable isotope data for precipitation 18op and drip water 18od from eight cave sites in the monsoon regions of china mrc with monthly to bi monthly sampling intervals from may 2011 to april 2014 to investigate the regional scale climate forcing on 18op and how the isotopic signals are transmitted to various drip sites the monthly 18op values show negative correlation with surface air temperature at all the cave sites except shihua cave which is opposite to that expected from the temperature effect in addition although the monthly 18op values are negatively correlated with precipitation at all the cave sites only three sites are significant at the 95 level these indicate that due to the various vapor sources a large portion of variability in 18op in the mrc cannot be explained simply by either temperature or precipitation alone all the thirty four drip sites are classified into three types based on the 18od variability about 82 of them are static drips with little discernable variation in 18od through the whole study period but the drip rates of these drips are not necessary constant their discharge modes are site specific and the oxygen isotopic composition of the stalagmites growing from them may record the average of multi year climatic signals which are modulated by the seasonality of recharge and potential effects of evaporation and in some cases infiltration from large rainfall events about 12 of the thirty four drip sites are seasonal drips although the amplitude of 18od is narrower than that of 18op the monthly response of 18od to coeval precipitation is not completely damped and some of them follow the seasonal trend of 18op very well these drips may be mainly recharged by present day precipitation mixing with some stored water thus the stalagmites growing under them may record portions of the seasonal climatic signals embedded in 18op about 6 of the thirty four drip sites are medium variability drips with constant and relatively low 18od values in the wet season but with variable and relatively high 18od values in the dry season reflecting flow switching in the karst or evaporation inside the cave

assessing the biomineralization processes in the shell layers of modern brachiopods from oxygen isotopic composition and elemental ratios implications for their use as paleoenvironmental proxies abstract fossil brachiopod shells are often used as valuable archives to reconstruct paleoenvironmental conditions in deep time however biomineralization processes can impact their fidelity as geochemical proxies brachiopod shells comprise an outer primary layer a secondary fibrous layer and sometimes a tertiary columnar layer therefore it is essential to assess the potential effects of the biomineralization processes in each of the different shell microstructures of modern brachiopods this study analyses the oxygen isotopic composition together with li ca na ca mg ca and sr ca data at high spatial 20 50 m resolution in seven modern brachiopod species focusing on differences between the primary secondary and tertiary layers in all studied species 18o values of the outer primary layer are consistently out of equilibrium with seawater also this shell layer is enriched in li na mg and sr contrary to the primary layer the innermost secondary layer is near or at oxygen isotopic and elemental equilibrium with ambient seawater the columnar tertiary shell layer if present has the least variable and the heaviest oxygen isotopic composition within the range of equilibrium values with seawater this tertiary layer however is depleted in minor and trace elements relative to the other shell layers thus the tertiary layer is more suitable for oxygen isotopic studies whereas the innermost secondary layer of the most mature parts of the shell is the best target in two layered shells while we do not observe any clear interspecific relationships between mg ca and sr ca ratios on one hand and environmental parameters such as temperature salinity and ph on the other hand there is a positive interspecific relationship between na ca and salinity and a negative interspecific relationship between li ca and temperature suggesting their potential use as proxies of physicochemical parameters of seawater

a high spatial resolution δ18o profile of a speleothem using an ion microprobe the oxygen isotopic composition of a stalactite from the soreq cave israel has been investigated by in situ high spatial resolution ion microprobe analysis the d 18 o record obtained on portions of the stalactite which were deposited during the time interval of 18 14 3 10 8 8 5 and 1 5 0 2 ka has a temporal resolution ranging from f1 to 25 years depending on the deposition rate during the period investigated comparison to results obtained by micro drilling and phosphoric acid reaction gas phase mass spectrometry indicates that the ion microprobe analyses are precise and accurate at the 0 4 0 5xlevel the high resolution of the ion microprobe profile enables the detection of short duration excursions toward low d 18 o values during deglaciation from 18 to 14 3 ka providing further evidence indicating the instability of the glacial climate d 2002 elsevier science b v all rights reserved

a new paradigm for δ18o in coral skeleton oxygen isotope fractionation response to biological kinetic effects abstract this study investigated the relative impact of temperature and light on oxygen isotope fractionation in the aragonite of the symbiotic coral acropora sp which was cultured under controlled conditions aragonite was randomly sampled and the oxygen isotopic composition 18o was analyzed at the micrometer scale measurements were collected from six cultured colonies using a factorial design of three temperatures 22 c 25 c and 28 c and two light intensities 200 and 400 mol photon m 2 s 1 observation of the newly formed skeletons revealed fibrous morphology the 18o distribution following a bin width of 0 25 in histograms was bimodal because the colonies were cultured under constant environmental conditions we suggest this bimodality in isotope distribution was caused by the diurnal cycle of 12 h light and 12 h dark that is necessary for coral health and to mimic natural conditions we assume that the two modal values correspond to the two fractionation end members present in daytime and nighttime fibers then we investigated the precipitation mechanism for each in contrast to a common assumption that the two fractionations are due to differences in ph created by more or less efficient ca2 pumping we demonstrate that the ph at the calcification site cannot explain the isotopic discrepancy between daytime and nighttime and conclude that aragonite precipitation does not obey classical thermodynamic rules we suggest that secretion of proteins by the calicoblastic layer different following the diurnal cycle can induce distinct biological kinetic processes we highlight the interplay of carbonic anhydrase ca and organic molecules to accelerate and facilitate the crystallization of coral aragonite only governed by coral metabolism

viscosity and thickness of the asthenosphere detected from the fennoscandian uplift the earth s response to the deglaciation in fennoscandia is modelled using a layered viscous model with an elastic lithosphere the modelled tilting of palaeoshorelines at particular locations peripheral to the former ice load and the pattern of the present rate of uplift consistent with the observations strongly suggest a low viscosity asthenosphere earth models without a low viscosity asthenosphere give significant mismatch to the present rate of uplift and are unable to mimic the observed tilting of palaeoshorelines models with a viscosity of the lower mantle of 1 0 2 0 1021 pa s and a viscosity of the upper mantle of 0 7 1 0 1021 pa s overlain by low viscosity asthenosphere with a thickness ranging from 25 to 100 km fit equally well with the observations it is suggested strongly that the asthenosphere has a thickness of less than 150 km and a viscosity of less than 7 0 1019 pa s

topographic development of the southern alps recorded by the isotopic composition of authigenic clay minerals south island new zealand abstract the southern alps are developing as a consequence of oblique collision between the pacific and australian plates the southern alps lie on the west side of the south island of new zealand and create a massive rain shadow where greater than 12 m year of rain falls on the west coast and semiarid conditions exist to the east the rain out effect across the mountains causes precipitation west of the southern alps to have d and 18 o values averaging 30 and 5 5 whereas precipitation in the rain shadow to the east is isotopically lighter d 72 and 18 o 9 8 such large differences in the isotopic composition of precipitation would not have existed prior to the development of significant topography we have examined the topographic evolution of the southern alps using oxygen isotope analyses of authigenic kaolinites formed in the rain shadow to the east of the mountains between the cretaceous low topography and the pleistocene changes in the isotopic composition of authigenic clay minerals forming in equilibrium with meteoric water in the stratigraphic sequence record the development of southern alps topography and the resultant rain shadow our oxygen isotope analyses of authigenic kaolinites show a 5 6 decrease in the early pliocene from 18 2 in older rocks to 12 3 in younger rocks in addition smectite is abundant in all samples from the late miocene to recent but is conspicuously absent in most older rocks suggesting a change to a generally drier climate roughly coincident with the isotopic shift in kaolinites this method may be useful in unraveling timing of development of mountain belts elsewhere in the world

global miocene tectonics and the modern world abstract an amazing congruence of seemingly unrelated diverse global events began in the middle and upper miocene and established our modern world two global orogenic belts were active mostly in the middle and upper miocene while backarc basins formed along the eastern margin of asia coincident with these events global temperatures cooled in both the ocean and atmosphere desertification occurred from central asia into and across most of northern africa and also in australia and in southern south america coincident with the expansion of the antarctic ice cap at 14 ma there was initial widespread deep sea erosion and changes in patterns of deep sea sedimentation muddy pelagic sedimentation increased six fold in the north and central atlantic and pacific oceans and global changes in circulation lead to more diatomites in the pacific and fewer in the atlantic by the end of the miocene most of the mediterranean sea had evaporated broadly coincident with these events many old large river systems were destroyed and new ones formed as much of the world s landscape changed collectively these global on shore tectonic and ocean atmospheric events provide the foundation for our modern world a mixture of new and rejuvenated orogenic belts and their far field effects distant epiorogenic uplift rain shadow deserts large alluvial aprons and distant deltas as inherited gondwanan landscapes persisted remote from plate boundaries thus at the end of the miocene much of the world s landscape except for that changed by pleistocene continental glaciation would be recognizable to us today we argue that all of these events had the same ultimate common cause an internal earth engine that drove plate motions in two broad ways first the opening and closing of seven key gateways to deep water oceanic currents radically altered global heat transfer and changed a lingering greenhouse to an icehouse world secondly these events were in part coincident with renewed heat flow in the african and pacific superplumes that energized global plate motions in the middle and upper miocene we hope this global synthesis will stimulate more research on the many global events of the miocene to understand better both our modern world and earlier global orogenies

sea level change glacial rebound and mantle viscosity fornorthern europe northwestern europe remains a key region for testing models of glacial isostasy because of the good geological record of crustal response to the glacial unloading since the time of the last glacial maximum models for this rebound and associated sea level change require a detailed knowledge of the ice sheet geometry including the ice thickness through time existing ice sheet reconstructions are strongly model dependent and inversions of sea level data for the mantle response may be a function of the model assumptions thus inverse solutions for the sea level data are sought that include both ice and earth model parameters as unknowns sea level data from fennoscandia the north sea the british isles and the atlantic and english channel coasts have been evaluated and incorporated into the solutions the starting ice sheet for fennoscandia is based on a reconstruction of a model by denton hughes 1981 that is characterized by quasi parabolic cross sections and symmetry about the load centre both global northwestern europe as a whole and regional subsets of the data solutions have been made for earth model parameters and ice height scaling parameters the key results are as follows 1 the response of the upper mantle to the changing ice and water loads is spatially relatively homogenous across scandinavia the north sea and the british isles 2 this response can be adequately modelled by an effective elastic lithosphere of thickness 65 85 km and by an effective upper mantle viscosity from the base of the lithosphere to the 670 km depth seismic discontinuity of about 3 4 1020 pa s the effective lower mantle viscosity is at least an order of magnitude greater 3 the ice thickness over scandinavia at the time of maximum glaciation was only about 2000 m much less than the 3400 m assumed in the denton hughes model 4 the ice profiles are asymmetric about the centre of the ice sheet with those over the western part being consistent with quasi parabolic functions whereas the ice heights over the eastern and southern regions increase much more slowly with distance inwards from the ice margin

climatic and topographic controls on the style and timing of late quaternary glaciation throughout tibet and the himalaya defined by 10be cosmogenic radionuclide surface exposure dating abstract temporal and spatial changes in glacier cover throughout the late quaternary in tibet and the bordering mountains are poorly defined because of the inaccessibility and vastness of the region and the lack of numerical dating to help reconstruct the timing and extent of glaciation throughout tibet and the bordering mountains we use geomorphic mapping and 10 be cosmogenic radionuclide crn surface dating in study areas in southeastern gonga shan southern karola pass and central western nyainqentanggulha shan and tanggula shan tibet and we compare these with recently determined numerical chronologies in other parts of the plateau and its borderlands each of the study regions receives its precipitation mainly during the south asian summer monsoon when it falls as snow at high altitudes gonga shan receives the most precipitation 2000 mm a 1 while near the margins of monsoon influence the karola pass receives moderate amounts of precipitation 500 600 mm a 1 and in the interior of the plateau little precipitation falls on the western nyainqentanggulha shan 300 mm a 1 and the tanggula shan 400 700 mm a 1 the higher precipitation values for the tanggula shan are due to strong orographic effects in each region at least three sets of moraines and associated landforms are preserved providing evidence for multiple glaciations the 10 be crn surface exposure dating shows that the formation of moraines in gonga shan occurred during the early mid holocene neoglacial and little ice age on the karola pass during the lateglacial early holocene and neoglacial in the nyainqentanggulha shan date during the early part of the last glacial cycle global last glacial maximum and lateglacial and on the tanggula shan during the penultimate glacial cycle and the early part of the last glacial cycle the oldest moraine succession in each of these regions varies from the early holocene gonga shan lateglacial karola pass early last glacial western nyainqentanggulha shan and penultimate glacial cycle tanggula shan we believe that the regional patterns and timing of glaciation reflect temporal and spatial variability in the south asian monsoon and in particular in regional precipitation gradients in zones of greater aridity the extent of glaciation has become increasingly restricted throughout the late quaternary leading to the preservation of old 100 ka glacial landforms in contrast in regions that are very strongly influenced by the monsoon 1600 mm a 1 the preservation potential of pre lateglacial moraine successions is generally extremely poor this is possibly because lateglacial and holocene glacial advances may have been more extensive than early glaciations and hence may have destroyed any landform or sedimentary evidence of earlier glaciations furthermore the intense denudation mainly by fluvial and mass movement processes which characterize these wetter environments results in rapid erosion and re sedimentation of glacial and associated landforms which also contributes to their poor preservation potential

a new approach to stable isotope based paleoaltimetry implications for paleoaltimetry and paleohypsometry of the high himalaya since the late miocene the change in oxygen isotopic composition of precipitation is modeled using equilibrium fractionation during rayleigh distillation linked to the thermodynamics of atmospheric ascent and water vapor condensation the primary controllers of the vertical variation in isotopic composition with elevation are the low elevation temperature and relative humidity as these control the vertical distribution of condensation an empirical fit of precipitation versus model condensation based on alpine stations is derived this fit is represented in the model as the weighted mean composition of condensation within a 1000 m thick air parcel 1500 500 m above the ground surface and is used for all other regions comparison of model versus observed modern precipitation reveals a close fit particularly of more highly elevated sites comparison of modern waters in the himalayas and southern tibet with model predictions particularly as revealed by comparison of observed and predicted hypsometry provides additional support to the validity of the model finally application of this model to estimates of paleo waters in the himalayas and southern tibet reveals that this region had already achieved its present hypsometry by the late miocene about 10 ma ago fl 2001 published by elsevier science b v

handbook of environmental isotope geochemistry vol 1 the terrestrial environment a p fritz and j ch fontes editors elsevier amsterdam 1980 xii 532 pp u s 90 25 dfl 185 00

glacio seismotectonics ice sheets crustal deformation and seismicity abstract the last decade has witnessed a significant growth in our understanding of the past and continuing effects of ice sheets and glaciers on contemporary crustal deformation and seismicity this growth has been driven largely by the emergence of postglacial rebound models pgm constrained by new field observations that incorporate increasingly realistic rheological mechanical and glacial parameters in this paper we highlight some of these recent field based investigations and new pgms and examine their implications for understanding crustal deformation and seismicity during glaciation and following deglaciation the emerging glacial rebound models outlined in the paper support the view that both tectonic stresses and glacial rebound stresses are needed to explain the distribution and style of contemporary earthquake activity in former glaciated shields of eastern canada and fennoscandia however many of these models neglect important parameters such as topography lateral variations in lithospheric strength and tectonic strain built up during glaciation in glaciated mountainous terrains glacial erosion may directly modulate tectonic deformation by resetting the orogenic topography and thereby providing an additional compensatory uplift mechanism such effects are likely to be important both in tectonically active orogens and in the mountainous regions of glaciated shields in general the short term response to ice fluctuations is similar to the earth s response to fluctuations in water reservoirs with the subsequent increase or decrease in seismicity which depends on the pre existing stress state when the ice fluctuations occur on the spatial scale and magnitude of the late pleistocene glaciation and deglaciation however the viscoelastic response of the earth especially the mantle causes significant changes in crustal deformation and earthquake activity that is spatially extensive and temporally complex the regions of greatest ice thickness and the regions marginal to the late pleistocene ice sheets indicate the most dramatic evidence of earthquake faulting the mantle response to these large ice mass fluctuations and the change in mass between the oceans and land caused and continues to cause measureable crustal deformation at hundreds of kilometres from the ice margins for both tectonically active and cratonic regions palaeoseismic investigations of late pleistocene and holocene faults are an important tool in evaluating earthquake hazard the predicted response of the earth over this time however is very dependent on the model assumed for most regions far more carefully designed field observations are needed to constrain the existing rheological and ice models

tectonically induced climate and its control on the distribution of depositional systems in a continental foreland basin cloverly and lakota formations lower cretaceous of wyoming u s a abstract continental sediments of the cloverly and lakota formations lower cretaceous in wyoming are subdivided into three depositional systems perennial to intermittent alluvial intermittent to ephemeral alluvial and playa chert bearing sandstones conglomerates carbonaceous mudrocks blocky mudrocks and skeletal limestones were deposited by perennial to intermittent alluvial systems carbonaceous mudrocks contain abundant wood fragments cuticle and cortical debris and other vascular plant remains representing deposition in oxbow lakes abandoned channels and on floodplains under humid to seasonal conditions intraformational conglomerates sandstones bioturbated and blocky mudrocks with caliche nodules and bioturbated limestones characterize deposition in intermittent to ephemeral alluvial systems bioturbated limestones are encased in bioturbated mudrocks with abundant pseudo slickensides the presence of caliche nodules in some of the blocky to bioturbated mudrocks is consistent with supersaturation and precipitation of calcium carbonate from groundwater under semi arid conditions caliche nodules pseudo slickensides and carbonate rich floodplain sediments are interpreted to have been deposited by intermittent to ephemeral alluvial systems under seasonal to semi arid climatic conditions laminated mudrocks siltstones vuggy carbonates bedded to nodular evaporites pebbly mudrocks and diamictites were deposited in evaporative alkaline lakes or playas pebbly mudrocks and diamictites are interpreted to represent deposition from channelized and unchannelized hyperconcentrated flows on a playa resulting from intense rain events within the basin the areal abundance and distribution of these depositional systems change systematically across the overfilled portion of the early cretaceous cordilleran foreland basin in wyoming the lower part a interval of the cloverly and lakota formations is characterized by deposits of perennial to intermittent rivers that existed 300 to 1000 km east of the sevier fold and thrust belt proximal to the sevier fold and thrust belt the a interval of the cloverly formation and upper ephraim formation of the gannett group are typified by deposits of intermittent to ephemeral rivers and their associated floodplains in the middle part b interval of the cloverly formation intermittent to ephemeral alluvial systems expand to 600 km into the basin the upper part c interval of the cloverly formation is characterized by playa deposits in the bighorn and wind river basins and intermittent to ephemeral alluvial deposits along the front of the ancestral sevier mountains deposits of perennial to intermittent alluvial systems in the c interval of the cloverly and lakota formations are restricted to the black hills region almost 900 km to the east of the sevier mountains the change in the areal distribution of depositional systems through time within this continental foreland basin may be attributed to the development of a rain shadow associated with the uplift of the sevier mountains in the early cretaceous

focus oxygen isotope microanalysis across incremental layers of human bone exploring archaeological reconstruction of short term mobility and seasonal climate change abstract in archaeological populations the oxygen isotope composition 18o of human bones and teeth can be used to reconstruct climatic conditions and landscape mobility by serving as a proxy for changes in 18o of consumed water until now providing this information at the seasonal scale across broad periods of an individual s life has been considered impossible because bone remodeling was thought to completely disrupt meaningful patterns preserved in bone microstructure recent studies however have described large often 1 mm deposits of incremental primary bone persisting well into adulthood and new technology permits finer scale analysis than ever before our objective was to determine the 18o variation across human primary bone layers using high spatial resolution secondary ion mass spectrometry sims results show patterned sinusoidal periodicity similar to expectations for weather induced fluctuations in seasonal drinking water the bone formation rate suggested by the isotopic variation in our study is consistent with other histological assessments of primary lamellar bone formation the technique thus enables sampling of 18o at approximately monthly intervals over more than a decade of bone deposition because bone is the most commonly recovered archaeological tissue applications of this method even using fragmentary remains have the potential to enable more detailed reconstructions of political economic health and sociocultural change at life history levels future applications may also include identification of remains in historic and forensic contexts and determination of developmental or pathogenic rates in ancient or modern health investigations

u th isotope systematics from the soreq cave israel and climatic correlations precise 230 th 234 u ages were obtained on thirty one growth laminae in speleothem samples which are self consistent with the detailed layer stratigraphy samples with low 232 th 238 u ratios give ages with analytical uncertainties of 40 years at 2 ky and 1000 years at 90 ky some growth zones with high but variable 232 th 238 u were dated by intermal isochrons this permits the determination of the initial 230 th 232 th assuming equilibrium of 232 th and 238 u series in the source of the high 232 th component this shows initial 230 th 232 th in activity units of from 1 3 to 2 9 the calculated atomic ratios of 232 th 238 u for the high 232 th component range from 1 08 to 2 4 which is well below the average crustal value speleothem materials with high 232 th 238 u are found to exhibit clear correlations of 232 th with si al and fe while 238 u correlates with sr and ba analyses of soreq cave drip waters show that the particulates in the waters have high 232 th concentrations and a 232 th 238 u ratio much lower than that found in the high 232 th component in speleothems but with 230 th 232 th 1 0 to 2 4 we infer that the trapped high th component in speleothems is from particulate matter in water with a large concentration of adsorbed u and not simply from detrital material the speleothems have only small234u excess the initial 234 u 238 u 0 show a range of 1 02 to 1 14 that was found to correlate with age over the past 25 ky the youngest samples have values in the same range as the modern drip waters there appears to be a correlation of 234 u 238 u 0 with the 18 o values there is a drop of 18 o in the time interval 20 to 15 ky which then remains relatively constant to recent times as the high 18 o values have been related to rainfall and associated climatic conditions we suggest that the 234 u 238 u in the speleothem reflects the effects of rainfall and soil weathering conditions on drip water composition and may provide a proxy for climate change

slip rate variations on normal faults during glacial interglacial changes in surface loads geologic and palaeoseismological data document a marked increase in the slip rates of the wasatch fault and three adjacent normal faults in the basin and range province during the late pleistocene early holocene epochs the cause of this synchronous acceleration of fault slip and the subsequent clustering of earthquakes during the holocene has remained enigmatic although it has been suggested that the coincidence between the acceleration of slip and the shrinkage of lake bonneville after the last glacial maximum may indicate a causal relationship here we use finite element models of a discrete normal fault within a rheologically layered lithosphere to evaluate the relative importance of two competing processes that affect fault slip postglacial unloading the removal of mass which decreases the slip rate and lithospheric rebound which promotes faster slip we show that lithospheric rebound caused by regression of lake bonneville and deglaciation of adjacent mountain ranges provides a feasible mechanism for the high holocene rates of faulting in the wasatch region our analysis implies that climate controlled changes in loads applied to earth s surface may exert a fundamental control on the slip history of individual normal faults

evaluation of sampling resolution in coral stable isotope records a case study using records from new caledonia and tarawa we have generated a 40 year long monthly stable isotope record from a porites lutea coral collected offshore of amedee new caledonia 22 s 167 e to investigate the relation between sampling resolution in coral isotope studies and retrieval of sea surface environmental information we interpret the high correlation between our oxygen isotope record and a twenty year long sea surface temperature record at the monthly timescale r 0 88 to indicate that our coral isotope record is an accurate monitor of environmental conditions offshore of amedee the character of the signal and the percent variance explained in the record at the annual band at the quasi biennial oscillation band qbo 2 0 2 4 years and at the el nino southern oscillation band enso 3 8 years changes little in response to a reduction in sampling density from monthly to bimonthly to quarterly similar results have been obtained in a reanalysis of a coral isotope record from tarawa kiribati our results indicate that a significant amount of the information obtained from high density sampling can also be retrieved from lower density sampling in particular bimonthly sampling yields virtually no drop off in variance explained and quarterly sampling is satisfactory for resolving interannual and decadal scale trends in time series the proposed sampling approach may enable a more rapid filling in of numerous spatial holes in coral sampling sites needed for reconstruction of long term decadal scale variations in climate

investigation of early eocene water vapor transport and paleoelevation using oxygen isotope data from geographically widespread mammal remains the oxygen isotope composition 18 o of apatite from mammalian tooth enamel can be used to infer the 18 o value of ingested water which is in turn related to that of precipitation stored in surface reservoirs therefore the 18 o value of phosphate from fossil tooth enamel can be used to infer the 18 o value of these reservoirs in the past in this paper tooth enamel from a semiaquatic mammal taxon coryphodon collected from five early eocene localities in north america is used to construct patterns in 18 o values of river water for this time period at all localities the 18 o value of river water 18 o r is estimated to have been higher during the early eocene relative to present day north american rivers although the 18 o vs latitude gradient was shallower during the eocene higher 18 o r values are consistent with warmer eocene air masses being able to hold more water vapor and with an increase in the poleward transport of both moisture and latent heat the regular decrease in 18 o r with latitude indicates that global atmospheric circulation patterns and hydrological transport were not much different from those of the present although the shallower 18 o vs latitude gradient during the eocene may reflect regional differences in precipitation evaporation and river recharge at a more regional scale the 18 o value of river water can provide insight into topographic relief during the early eocene in the case of intermontane basins of wyoming differences in average 18 o r values between basins indicate that laramide mountain relief was on the order of 475 m it is suggested that anomalously low 18 o r values reported previously do not provide unambiguous evidence for permanent snow at higher elevations and may instead reflect brief episodes of cooler winters and or altered atmospheric circulation patterns

fennoscandian earthquakes whole crustal rupturing related to postglacial rebound local and regional earthquake locations provide seismic evidence that large shield earthquakes have occurred in northern fennoscandia these paleoearthquakes with fault lengths of up to 160 kilometers and average displacements of up to 15 meters were triggered by nonisostatic compressive stresses caused by the removal of the ice at the end of the last deglaciation the fennoscandian faults were probably formed by single events that ruptured through most of the crust the largest event moment magnitude mw 8 2 was larger than other known stable continent earthquakes outside failed rifts or extended crust

comparison of δ18o analyses on individual planktic foraminifer orbulina universa shells by sims and gas source mass spectrometry author s wycech jb kelly dc kozdon r orland ij spero hj valley jw abstract 2018 elsevier b v the oxygen isotope 18o compositions of final chamber fragments of individual shells of the planktic foraminifer orbulina universa were measured in situ via secondary ion mass spectrometry sims and by traditional gas source mass spectrometry gsms entailing acid digestion of sampled calcite the paired sims gsms analyses were performed on final chamber fragments of fossil shells taken from the top of a sediment core holocene as well as shells grown in laboratory culture multiple iterations of sims gsms analyses were conducted on final chamber fragments treated with a variety of cleaning protocols the series of paired analyses yielded an average sims gsms 18o offset 18osims gsms of 0 9 0 1 2 se the volume of material analyzed in 10 m sims spots is 105 times smaller than that analyzed by gsms hence the extent to which these 18osims gsms values represent real differences in analyte vs instrumental factors remains unclear possible contributing factors to the sims gsms 18o difference include sample standard mismatch by sims differences in standardization of sims and gsms and non calcite contaminants in samples although the two datasets are consistently offset sims values reproduce inter shell 18o variability delineated by shell fragment gsms values this strong positive covariance proved useful for bringing the two datasets into agreement i e 18osims gsms 0 and confirms that sims based foraminifer 18o values record changes in calcification temperature and or 18o of seawater whether shells of foraminifer taxa with differing microcrystalline structures chemical composition and or preservation histories register a similar 18osims gsms value is a subject of ongoing testing

mid holocene climate variations revealed by high resolution speleothem records from soreq cave israel and their correlation with cultural changes mid holocene 7000 4000 yr bp paleoclimate conditions were reconstructed for the eastern mediterranean region through a high resolution 3 20 yr oxygen and carbon isotopic record in a speleothem

seasonal resolution of eastern mediterranean climate change since 34 ka from a soreq cave speleothem the combination of ion microprobe analysis of d 18 o and confocal laser fluorescent microscope imaging of annual growth bands in a soreq cave speleothem provides sub annual scale climate information between 34 and 4 ka this high resolution methodology is ideal both for comparing seasonal climate patterns across broad windows of time and examining rapid climate events such as the younger dryas termination in detail the sub annual d 18 o gradients we report represent a combination of seasonal variability in rainfall amount and air temperature a distinct change in both the pattern of fluorescent banding and the gradient of d 18 o measured in situ across single annual growth bands indicates a change in seasonal climate patterns of the eastern mediterranean region following heinrich event 1 and again after the younger dryas throughout the holocene wet winters and dry summers characterized regional climate during the younger dryas we find that regional climate may have been more arid than in the holocene but the fluorescent banding pattern indicates that the supply of dripwater to the cave was more consistent year round we suggest that a reduced gradient of seasonal precipitation occasional snowfall and vegetation differences may have all contributed to the isotope and fluorescent banding patterns observed during heinrich event 1 and the last glacial stadial detailed investigation of the younger dryas termination reveals a rapid onset of regional environmental change fluorescent band counting indicates that the younger dryas termination as recorded by rainfall in the

climatic conditions during marine oxygen isotope stage 6 in the eastern mediterranean region from the isotopic composition of speleothems of soreq cave israel at several times during marine oxygen isotope stage 6 the eastern mediterranean region was influenced by two extreme climatic systems the large ice sheet over northern europe and the wet tropics associated with african monsoons during this interval two major climatic events occurred in the region the sapropel s6 layer formed ca 176 ka in the eastern mediterranean basin owing to the increase in the african monsoon and another event although not large enough to form sapropel occurred ca 151 ka the isotopic composition of soreq cave speleothems seems to record these events as very low 18 o 13 c values dated as ca 178 and 152 ka the very low 18 o 13 c values of 6 and 11 to 12 respectively are typical of interglacial intervals but here they were recorded during a glacial interval such low peaks indicate that in this part of the eastern mediterranean region i e israel the rainfall amount increased dramatically moreover the isotopic record of the speleothems also shows that during the entire stage 6 although the climate was as cold as much of the last glacial the conditions were never as dry

tomographic inversion of seismic p and s wave velocities from the baltic shield based on fennolora data abstract tomographic travel time inversion of seismic compressional p and shear s wave data from the long range deep seismic sounding experiment fennoscandian long range fennolora reveals the velocity structure of the crust and upper mantle in the baltic shield pronounced scattering and delay in travel times of seismic p and s wave phases together with strong attenuation of s wave phases beyond ca 800 km offset are attributed to a low velocity zone lvz below the 8 discontinuity at a depth of ca 100 km travel time inversion of p and s wave first arrivals shows that the 8 discontinuity represents the top of a zone with negative or very small vertical velocity gradients and a vp vs ratio of 1 74 1 77 we observe clear linear refracted p wave phases i e the lehmann refraction at offsets beyond 1100 1300 km which suggest that the base of the low velocity zone is at ca 150 km depth in the baltic shield no refracted s wave phases are observed beyond 1200 km offset which we attribute to strong s attenuation within the zone below the 8 discontinuity these features are interpreted by the presence of small amounts of partial melts almost molten rocks or possibly free fluids in the 100 150 km depth interval local variations in the vp vs ratio of the crust and uppermost mantle correlate with proterozoic terranes which collided and were amalgamated during the precambrian plate tectonic events that led to the assemblage of the baltic shield

climatic and environmental controls on speleothem oxygen isotope values variations in speleothem oxygen isotope values d 18 o result from a complicated interplay of environmental controls and processes in the ocean atmosphere soil zone epikarst and cave system as such the controls on speleothem d 18 o values are extremely complex an understanding of the processes that control equilibrium and kinetic fractionation of oxygen isotopes in water and carbonate species is essential for the proper interpretation of speleothem d 18 o as paleoclimate and paleoenvironmental proxies and is best complemented by study of site specific cave processes such as infiltration flow routing drip seasonality and saturation state and cave microclimate among others this review is a process based summary of the multiple controls on d 18 o in the atmosphere soil epikarst and speleothem calcite illustrated with case studies primary controls of d 18 o in the atmosphere include temperature and relative humidity through their role in the multiple isotope effects variability and modifications of water d 18 o values in the soil and epikarst zones are dominated by evaporation mixing and infiltration of source waters the isotopically effective recharge into a cave system consists of those waters that participate in precipitation of caco3 resulting in calcite deposition rates which may be biased to time periods with optimal dripwater saturation state recent modeling experimental and observational data yield insight into the significance of kinetic fractionation between dissolved carbonate phases and solid caco3 and have implications for the hendy test to assist interpretation of speleothem d 18 o time series quantitative and semi quantitative d 18 o climate calibrations are discussed with an emphasis on some of the difficulties inherent in using modern spatial and temporal isotope gradients to interpret speleothems as paleoclimate proxy records finally several case studies of globally significant speleothem paleoclimate records are discussed that show the utility of d 18 o to reconstruct past climate

rainfall recharge relationships within a karstic terrain in the eastern mediterranean semi arid region israel δ 18o and δd characteristics annual rainfall variations and processes in the upper vadose zone exert a profound influence on the chemical and isotopic compositions of waters of carbonate aquifers in semi arid climatic zones in order to define these processes we have studied the surface temperatures during rainfall events the isotopic composition of rain infiltrating and groundwaters this study was carried out within a karstic terrain soreq cave israel located in cenomanian dolomitic rocks approximately 40 km inland of the mediterranean sea and 400 m above sea level the climate is typical of the eastern mediterranean semi arid conditions with a rainy winter and dry summer and the average annual rainfall in the area is 500 mm close monitoring indicates that the d and 18o values of individual rainstorm events decrease with increasing rainfall annual average isotopic values of years with rainfall of 500 600 mm do not vary systematically years with extreme rainfall values define a negative covariation between the 18o and rainfall the d 18o relationship of all rain events of more than 20 mm fall on the mediterranean meteoric water line mmwl with a slope of 8 and d excesses of 20 30 these rain events occur when mid winter surface temperatures are 5 to 10 c rainfall events of less than 20 mm mainly occurring at above 10 c have slopes of less than 8 and smaller d excess as a consequence of evaporation processes beneath the clouds two main water types infiltrating into the cave are recognized slow and fast drip slow drip occurs from the tips of stalactites and takes place throughout the year these waters represent seepage water that remains in the upper vadose zone for up to several decades fast drip emanates from fissures in the cave roof during the winter seasons these waters represent vadose flow with a short residence time of less than 1 year the infiltration of the fast drip water into the cave depends on the fracture system of the rock cover and on the intensity of the rainstorms in the inner parts of the cave where the rock cover is thick fast drip starts only after several massive 20 mm rainstorms whereas below a thin roof the response time of fast drip is a few hours to a few days after intensive rainstorms both fast and slow drip water fall on the mmwl indicating that they are derived mainly from the relatively intensive rainstorms that compose about 23 of the annual rainfall although fast dri water represents massive rainstorms their 18o and d values are nonetheless higher by 1 and 10 respectively relative to the average rainwater compisition this indicates that the fast drip water consists predominantly of water derived from intensive rainstorms admixed with a minor component of isotopically 18o and d enriched water which is represented by the slow drip waters the fast drip waters are derived mainly from massive rain events at surface temperatures of 5 to 10 c which thermally equilibrate with the host rock and upon reaching the cave they have already acquired the mean temperature 20 c of the cave

seasonal climate signals 1990 2008 in a modern soreq cave stalagmite as revealed by high resolution geochemical analysis article high resolution isotopic and geochemical analyses in a modern 1990 2008 soreq cave stalagmite are com pared to instrumental records of rainfall and dripwater from the cave with the aim of determining how seasonal resolutionclimateinformationistransmittedtospeleothemgeochemistry insitu micron scaleanalysis of oxygen isotope ratios 18 o and trace elements by ion microprobe in combination with a continuous linear traverse of trace element concentrations by laser ablation icp ms la icp ms allow the definition of geochem ical pathways within the cave fluorescent banding imaged by confocal laser fluorescent microscopy clfm as well as

palaeo climate reconstruction from stable isotope variations in speleothems a review abstract speleothems are now regarded as valuable archives of climatic conditions on the continents offering a number of advantages relative to other continental climate proxy recorders such as lake sediments and peat cores they are ideal materials for precise u series dating yielding ages in calendar years thereby circumventing the radiocarbon calibration problems associated with most other continental records stable isotope studies in speleothems have shifted away from attempting to provide palaeo temperature reconstructions to the attainable goal of providing precise estimates for the timing and duration of major o isotope defined climatic events characterised by high signal to noise ratios e g glacial interglacial transitions dansgaard oeschger oscillations the 8200 year event unlike the marine records speleothem data sets are not tuned and their independent chronology offers opportunities to critically assess leads and lags in the climate system that in turn can provide important insights into forcing and feedback mechanisms improved procedures for the extraction and measurement of stable isotope ratios in fluid inclusions trapped in speleothems are likely to provide in the near future a much enhanced basis for the quantitative interpretation of o isotope ratios in speleothem calcite the latter developments open up once again the tantalising prospect of palaeo temperature estimates but more importantly perhaps provide a direct test for a new generation of general circulation models whose hydrological cycles will incorporate the water isotopes the literature is reviewed briefly to provide for the reader a sense of the current state of the art and to provide some pointers for future research directions

postseismic mantle relaxation in the central nevada seismic belt holocene acceleration of deformation and postseismic relaxation are two hypotheses to explain the present day deformation in the central nevada seismic belt cnsb discriminating between these two mechanisms is critical for understanding the dynamics and seismic potential of the basin and range province interferometric synthetic aperture radar detected a broad area of uplift 2 to 3 millimeters per year that can be explained by postseismic mantle relaxation after a sequence of large crustal earthquakes from 1915 to 1954 the results lead to a broad agreement between geologic and geodetic strain indicators and support a model of a rigid basin and range between the cnsb and the wasatch fault

paleoseismology of the northern piedmont of tianshan mountains northwestern china the northern piedmont of the tianshan mountains consists of three rows of cenozoic ew striking fold and reverse fault zones with en echelon right lateral steps the southernmost row involves sediments as young as lower pleistocene but there is no evidence of activity along this row during the last 30 000 years the central row is composed of three linear anticlines houerguos manas and tugulu and associated reverse faults the northernmost row includes the dushanzi halaande and anjihai anticlines and their associated reverse faults abundant fault scarps and folds of late pleistocene to holocene river terraces across the anticlines within the central and the northernmost rows indicate recent folding and reverse faulting we divide the northern piedmont into the dushanzi and manas fold and reverse fault zone in the dushanzi zone we excavated 15 trenches across scarps controlled by reverse faults and back thrusts by comparing 11 trench logs among the 15 trenches we identify three paleoearthquakes since 13 000 years b p the first event occurred between 11 300 and 13 300 years b p and the second and the third events occurred 6300 8400 and 3000 5000 years b p respectively considering the uncertainties of the data the average recurrence interval for large earthquakes in the dushanzi zone is about 4000 years a large earthquake along this zone is expected in the near future because the elapsed time since the last surface rupturing event is already 3000 4000 years three large trenches and several small trenches excavated across the fault scarps along the manas fold and reverse fault zone reveal four events the first second and third events occurred at 18 000 13 000 years b p 11 300 10 500 years b p and 6900 3600 years b p respectively the fourth the latest one is the 1906 m 7 7 manas earthquake field investigation suggests that the 1906 manas earthquake occurred along a blind thrust fault this earthquake formed three discontinuous zones of fresh surface ruptures the longest of which is only 8 km long along the eastern segment of the tugulu reverse fault and was associated with a zone of uplift 130 km long related to the manas earthquake the average recurrence interval along this zone is probably 5000 6000 years therefore it is unlikely that a large earthquake will occur along this zone in the near future because the manas earthquake occurred only 89 years ago

the thermal and cementation histories of a sandstone petroleum reservoir elk hills california part 2 in situ oxygen and carbon isotopic results abstract liquid hydrocarbon accumulations within the elk hills and north coles levee oil fields southern san joaquin basin are largely isolated within calcite cemented reservoirs comprised of late miocene stevens sandstone we undertook ion microprobe carbon and oxygen isotope ratio measurements on calcite cements to assess both the source of the carbon and the temperature of cementation by combining thermal history results from 40 ar 39 ar analyses reported in the companion study with calculated cementation temperatures based on our oxygen isotope measurements a model cementation history is derived which indicates that carbonate precipitation occurred primarily between 4 and 6 5 ma conventional oxygen isotopic measurements yield a more restricted range of isotopic compositions reflecting the averaging properties of that method the associated carbon isotopic measurements suggest that most of the early cements were derived from a marine carbonate source or a mixture of marine carbonate and lighter carbon from maturing hydrocarbons carbonates precipitated most recently and thus at the highest temperatures contain light carbon interpreted to result from thermal decomposition of kerogen in the interbedded shales based on the light carbon values

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

centennial scale holocene climate variability revealed by a high resolution speleothem δ18o record from sw ireland evaluating the significance of holocene submillennial 18 o variability in the greenland ice cores is crucial for understanding how natural climate oscillations may modulate future anthropogenic warming a high resolution oxygen isotope record from a speleothem in southwestern ireland provides evidence for centennial scale 18 o variations that correlate with subtle 18 o changes in the greenland ice cores indicating regionally coherent variability in the early holocene evidence for previously undetected early holocene cooling events is presented but mid to late holocene ice rafting in the north atlantic appears to have had little impact on 18 o at this ocean margin site

an interpretation and catalogue of paleoseismicity in sweden abstract paleoseismic data provide a long term record of seismic activity to predict hazards for periods longer than one to a few centuries in sweden the analysis reveals there was a drastic change in dominant seismic mode from a high to super high deglacial mode to a low to moderately low mode in present and late holocene time paleoseismic criteria and characteristics include numerous different sources of information viz primary faults bedrock deformation sedimentary deformation rock and sediment slides liquefaction sorting by shaking tsunamis differing geomorphic expressions disordering and ordering of magnetic particles by applying multiple criteria it was possible to identify 44 paleoseismic events including 23 events of estimated m 6 7 12 events of m 7 8 and 6 events of m 8 varve dating often allows a precision as to a single year in one case even to the season of a year the key for paleoseismic reconstruction and testing is the application of multiple criteria

review of paleoseismological and active fault studies in taiwan in the light of the chichi earthquake of september 21 1999 abstract this paper reviews the research on active and earthquake faults in taiwan conducted prior and after the 1999 chichi earthquake the chichi earthquake plays as a turning point of the relevant studies since the 1999 coseismic surface rupture exactly follows preexisting fault scarps created in turn by previous seismic events along the chelungpu fault this fact indicates that the precise mapping on the other active faults is fundamental to predict the location of surface rupture caused by large future earthquakes since 1999 many trenching studies have been carried out along the chichi earthquake fault a few of them demonstrates that the penultimate event is as young as probably only 200 430 years old however some others show a rather old age of several hundreds years or even older for the last faulting event before 1999 more trenching studies are necessary for such a long fault in order to understand the possible segmentation features and the correlation of the paleoseismic events identified along the entire fault length in addition we further discuss the offshore faulting associated with seismic event along the eastern coast of taiwan where the multiple holocene terraces are well known

basalt vesicularity as a measure of atmospheric pressure and palaeoelevation the pressure in and thus the size of a bubble in a lava flow is determined by the atmospheric pressure and the hydrostatic pressure of the overlying lava if atmospheric sea level pressure is known or assumed vesicle size distributions in basalt flows can thus be used as an indicator of the palaeoelevation of emplacement1 here we show by analysis of the vesicle size distribution of basalt samples collected from the summit and base of mauna loa volcano in hawaii that the technique provides estimates of ambient pressure that are accurate to within 0 1 bar and thus estimates of elevation with a resolution of about 1 400m this palaeoaltimetric technique should find useful application in palaeogeographical reconstruction2 for times when sea level pressure was similar to the present value conversely if the elevation of emplacement is known our technique should be able to provide a measure of sea level palaeopressure unlike palaeo botanical methods for estimating elevations3 6 this method does not have to assume a relationship between temperature and altitude on the other hand its use is restricted to lava flows that have had a simple emplacement history

the eastern mediterranean paleoclimate as a reflection of regional events soreq cave israel the climate of the eastern mediterranean region of the last 60 ky was determined by a high resolution study of the oxygen and carbon isotopic composition 1500 measurement pairs of speleothems from the soreq cave israel with chronology provided by 53 precise 230 th 234 u tims ages the high precision of the speleothem tims ages permits us to determine the timing of regional climatic events in the eastern mediterranean region and to see if they correlate with global events during the period from 60 to 17 ky the 18 o and 13 c values were generally 2 2 5 higher than during the period from 17 ky to present this is consistent with the climatic transition from glacial to interglacial within the 60 to 17 ky period the soreq cave stable isotope profile includes four cold peaks at 46 35 25 and 19 ky and 2 warm peaks at 54 and 36 ky in addition the period 17 ky has two more cold peaks at 16 5 and from 13 2 to 11 4 ky the ages of four of the six cold peaks correlate well with the ages of three heinrich events h1 h2 h5 and with the age of the younger dryas however the other two heinrich events are not reflected in the soreq cave record several other isotope peaks which appear during the last 7 ky are contemporaneous with regional climatic events in the middle east and north africa in addition to the drop in 18 o and 13 c observed between the last glacial and the holocene sharp simultaneous drops in 234 u 238 u 0 ratios sr concentrations and in 87 sr 86 sr are also observed suggesting that the latter are climate related these variations are interpreted in terms of major changes in the temperature the mean annual rainfall and its isotopic composition the isotopic composition of the mediterranean vapor source the soil moisture conditions and in the mixing proportions of sources with different 87 sr 86 sr ratios sea spray dust particles and dolomitic host rock

suppression of earthquakes by large continental ice sheets the interior regions of antarctica and greenland are aseismic no earthquake larger than body wave magnitude 4 5 5 0 is known for either except along coastal zones or continental shelves here i advance an explanation for this lack of seismic activity in terms of pressure effects produced by the continental ice sheets that mantle both continents

ion microprobe δ18o analyses to calibrate slow growth rate speleothem records with regional δ18o records of precipitation abstract paleoclimate reconstructions based on speleothems require a robust interpretation of their proxies detailed transfer functions of external signals to the speleothem can be obtained using models supported by monitoring data however the transferred signal may not be stationary due to complexity of karst processes therefore robust interpretations require the calibration of speleothem records with instrumental time series lasting no less than a decade we present the calibration of a speleothem 18 o record from postojna cave slovenia with the regional record of 18 o composition of precipitation during the last decades using local meteorological data and a regional 18 o record of precipitation we developed a model that reproduces the cave drip water 18 o signal measured during a two year period the model suggests that the average water mixing and transit time in the studied aquifer is 11 months additionally we used an ion microprobe to study the 18 o record of the top 500 m of a speleothem from the studied cave gallery according to u th dates and 14c analyses the uppermost section of the speleothem was formed during the last decades the 18 o record of the top 500 m of the speleothem has a significant correlation r 2 0 64 p value 18 o record of cave drip water therefore we confirm that the top 500 m of the speleothem grew between the years 1984 and 2003 and that the speleothem accurately recorded the variability of the 18 o values of regional precipitation filtered by the aquifer we show that the recorded speleothem 18 o signal is not seasonally biased and that the hydrological dynamics described during monitoring period were stationary during recent decades this research demonstrates that speleothems with growth rates

dating large infrequent earthquakes by damaged cave deposits the long term recurrence patterns of past earthquakes are of considerable consequence for hazard assessments and have implications for earthquake physics we introduce a rigorously dated record of earthquakes from an extensive number of well preserved pre seismic and postseismic precipitates from caves located off the dead sea transform we dated events directly at the paleoseismic contact by means of a novel correlation method with the oxygen isotope record of the speleothems recovered in one of the caves within the 185 k y covered we dated 38 seismite samples these stem from 13 18 earthquakes with a mean recurrence interval of 10 14 k y we show that the deformational events dated in the study caves complement independent near fault paleoseismic records by tem poral correlation with the earthquakes recorded therein this opens up a significant new avenue of earthquake research that will provide precise dating and observational con straints on large infrequent earthquakes

palaeoclimate determination from cave calcite deposits calcite deposits formed in limestone caves have been found to be an excellent repository of palaeoclimatic data for terrestrial environments the very presence of a relict deposit indicates non glacial conditions at the time of formation and both 14c and uranium series methods can be used to date the deposit and hence the age of these climatic conditions variations in 13c and 18o content of the calcite in 2h and 18o content of fluid inclusions in trace element concentrations and more recently in pollen assemblages trapped in the calcite are all potentially available as synchronous palaeoclimatic indicators previous work has tended to concentrate mainly on abundance of deposits as a palaeoclimatic indicator for the last 300 000 years this literature is briefly reviewed here together with the theory and methods of analysis of the u series and stable isotopic techniques the combined use of u series ages and 13c and 18o variations in cave calcites illustrates the potential for palaeoclimate determination previously unpublished results of stable isotopic variations in dated calcites from caves in northern england indicate the level of detail of stable isotopic variations and time resolution that can be obtained and the complexity of interpretation that may arise tentative palaeoclimatic signals for the periods 90 125 ka and 170 300 ka are presented more comprehensive studies are needed in future work especially in view of the difficulty in obtaining suitable deposits and the ethics of cave deposits conservation

in situ measurement of seasonal δ18o variations and analysis of isotopic trends in a modern speleothem from southwest australia we present a record of seasonal and inter annual oxygen o and carbon c isotope ratios from an 81 year old stalagmite from moondyne cave southwest australia the growth history of stalagmite mnd s1 is known since it grew on a cave boardwalk that was installed in 1911 and removed in 1992 this stalagmite provides an excellent test of speleothem climate proxies because the regional climate is strongly seasonal wet winter dry summer and has experienced a 200 mm 20 reduction of mean rainfall since the mid 1960s and a 0 8 c temperature rise since 1953 seasonal variations in calcite o were measured in situ by high spatial resolution ion microprobe whilst inter annual variations of o and c were measured by conventional gas source mass spectrometry comparison of the speleothem stable isotopes and instrumental temperature records reveals that o variations are too large to be driven by temperature alone and are in the opposite sense however daily rainfall o measurements show that the mean seasonal range in o of rainfall in southwest australia is large 2 and inversely correlated with rainfall amount a rainfall driver for the speleothem o is confirmed by the detection of seasonal shifts of 0 7 1 5 in speleothem that track rainfall o smoothed by storage in the overlying limestone the seasonal range in speleothem o is larger than any inter annual and decadal variation observed in the record the prominent annual cycles in speleothem o revealed by ion microprobe analysis indicate that subtle changes in the frequency of intense winter rainfall events or possibly also moisture sources could produce significant changes in mean speleothem o the ion microprobe results also raise the possibility that the masses of speleothem calcite deposited in winter and summer could vary as a function of the seasonal drip rate and carbonate saturation state of these waters if this is the case then small changes in the relative masses of calcite deposited in winter and summer could produce significant shifts in mean o and c that have a complex relation to climate this finding should be generally applicable to the interpretation of long term trends in speleothem geochemical records for shallow cave sites where seasonal variations in geochemical tracers are relatively large including most of the sub tropical monsoon belts and mid to high latitudes with distinct rainfall seasons

effect of ice sheet growth and melting on the slip evolution of thrust faults abstract field investigations suggest that postglacial unloading and rebound led to the formation or re activation of reverse faults even in continental shields like scandinavia here we use finite element models including a thrust fault embedded in a rheologically layered lithosphere to investigate its slip evolution during glacial loading and subsequent postglacial unloading the model results show that the rate of thrusting decreases during the presence of an ice sheet and strongly increases during deglaciation the magnitude of the slip acceleration is primarily controlled by the thickness of the ice sheet the viscosity of the lithospheric layers and the long term shortening rate in contrast the width of the ice sheet the rate of deglaciation or the fault dip have an only minor influence on the slip evolution in all experiments the slip rate variations are caused by changes in the differential stress the modelled deglaciation induced slip acceleration agrees well with the occurrence of large earthquakes soon after the melting of the fennoscandian ice sheet which led to the formation of spectacular fault scarps in particular in the lapland fault province furthermore our model results support the idea that the low level of seismicity in currently glaciated regions like greenland and antarctica is caused by the presence of the ice sheets based on our models we expect that the decay of the greenland and antarctica ice sheets in the course of global warming will ultimately lead to an increase in earthquake frequency in these regions

climate deterioration in the eastern mediterranean as revealed by ion microprobe analysis of a speleothem that grew from 2 2 to 0 9 ka in soreq cave israel abstract analysis of oxygen isotope ratios 18 o by ion microprobe resolves a sub annual climate record for the eastern mediterranean from a soreq cave stalagmite that grew between 2 2 and 0 9 ka in contrast to conventional drill sampling methods that yield a total variation of 1 0 in 18 o calcite values across our sample the methods described here reveal up to 2 15 variation within single annual growth bands values of 18 o measured by ion microprobe vary in a regular saw tooth pattern that correlates with annual fluorescent growth banding where calcite grades from light to dark fluorescence modern records of precipitation and of cave dripwater indicate that variable 18 o calcite values record regular seasonal differences in 18 o rainfall modified by mixing in the vadose zone large differences in 18 o values measured across a single band i e between the dark and light fluorescent calcite or 18 o dark light are interpreted to indicate wetter years while smaller differences represent drier years oxygen isotopes record 1 month scale growth increments 2 changes in 18 o dark light that represent seasonality 3 a systematic long term decrease in maximum 18 o dark light values and 4 an overall increase in average 18 o calcite values through time these results suggest a drying of regional climate that coincides with the decline of the roman and byzantine empires in the levant region