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

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

reducing uncertainty in the climatic interpretations of speleothem δ18o 1 we explore two principal areas of uncertainty associated with paleoclimate reconstructions from speleothem 18o 18ospel potential non stationarity in relationships between local climate and larger scale atmospheric circulation and routing of water through the karst aquifer using a 18ospel record from turkey the csiro mk3l climate system model and the karstfor karst hydrology model we confirm the stationarity of relationships between cool season precipitation and regional circulation dynamics associated with the north sea caspian pattern since 1 ka stalagmite 18o is predicted for the last 500 years using precipitation and temperature output from the csiro mk3l model and synthetic 18o of precipitation as inputs for the karstfor model interannual variability in the 18ospel record is captured by karstfor but we cannot reproduce the isotopically lighter conditions of the sixteenth to seventeenth centuries we argue that forward models of paleoclimate proxies such as karstfor embedded within isotope enabled general circulation models are now required

mantle dynamics uplift of the tibetan plateau and the indian monsoon convective removal of lower lithosphere beneath the tibetan plateau can account for a rapid increase in the mean elevation of the tibetan plateau of 1000 m or more in a few million years such uplift seems to be required by abrupt tectonic and environmental changes in asia and the indian ocean in late cenozoic time the composition of basaltic volcanism in northern tibet which apparently began at about 13 ma implies melting of lithosphere not asthenosphere the most plausible mechanism for rapid heat transfer to the midlithosphere is by convective removal of deeper lithosphere and its replacement by hotter asthenosphere the initiation of normal faulting in tibet at about 8 3 ma suggests that the plateau underwent an appreciable increase in elevation at that time an increase due solely to the isostatic response to crustal thickening caused by india s penetration into eurasia should have been slow and could not have triggered normal faulting another process such as removal of relatively cold dense lower lithosphere must have caused a supplemental uplift of the surface folding and faulting of the indo australian plate south of india the most prominent oceanic intraplate deformation on earth began between about 7 5 and 8 ma and indicates an increased north south compressional stress within the indo australian plate a tibetan uplift of only 1000 m if the result of removal of lower lithosphere should have increased the compressional stress that the plateau applies to india and that resists india s northward movement from an amount too small to fold oceanic lithosphere to one sufficient to do so the climate of the equatorial indian ocean and southern asia changed at about 6 9 ma monsoonal winds apparently strengthened northern pakistan became more arid but weathering of rock in the eastern himalaya apparently increased because of its high altitude and lateral extent the tibetan plateau provides a heat source at midlatitudes that should oppose classical symmetric hadley circulation between the equator and temperate latitudes and that should help to drive an essentially opposite circulation characteristic of summer monsoons for the simple case of axisymmetric heating no dependence on longitude of an atmosphere without dissipation theoretical analyses by hou lindzen and plumb show that an axisymmetric heat source displaced from the equator can drive a much stronger meridianal monsoonlike circulation than such a source centered on the equator but only if heating exceeds a threshold whose level increases with the latitude of the heat source because heating of the atmosphere over tibet should increase monotonically with elevation of the plateau a modest uplift 1000 2500 m of tibet already of substantial extent and height might have been sufficient to exceed a threshold necessary for a strong monsoon the virtual simultaneity of these phenomena suggests that uplift was rapid approximately 1000 m to 2500 m in a few million years moreover nearly simultaneously with the late miocene strengthening of the monsoon the calcite compensation depth in the oceans dropped plants using the relatively efficient c4 pathway for photosynthesis evolved rapidly and atmospheric co2 seems to have decreased suggesting causal relationships and positive feedbacks among these phenomena both a supplemental uplift of the himalaya the southern edge of tibet and a strengthened monsoon may have accelerated erosion and weathering of silicate rock in the himalaya that in turn enhanced extraction of co2 from the atmosphere thus these correlations offer some support for links between plateau uplift a downdrawing of co2 from the atmosphere and global climate change as proposed by raymo ruddiman and froehlich mantle dynamics beneath mountain belts not only may profoundly affect tectonic processes near and far from the belts but might also play an important role in altering regional and global climates

reconstruction of late holocene autumn winter precipitation variability in sw romania from a high resolution speleothem trace element record abstract we present the first high resolution trace element mg ca sr ca ba ca record from a stalagmite in southwestern romania covering the last 3 6 ka which provides the potential for quantitative climate reconstruction precise age control is based on three independent dating methods in particular for the last 250 yr where chemical lamina counting is combined with the identification of the 20th century radiocarbon bomb peak and 230th u dating long term cave monitoring and model simulations of drip water and speleothem elemental variability indicate that precipitation related processes are the main drivers of speleothem mg ca ratios calibration against instrumental climate data shows a significant anti correlation of speleothem mg ca ratios with autumn winter october to march precipitation r 0 61 p during the late holocene our data suggest a heterogeneous pattern of past regional winter hydroclimate in the carpathian balkan realm along with intermittent weakening of the dominant influence of north atlantic forcing in agreement with other regional paleo hydrological reconstructions the observed variability reveals periodically occurring strong nw se hydro climate gradients we hypothesize that this pattern is caused by shifts of the eastern edge of the area of influence of the nao across central eastern europe due to the confluence of north atlantic forcing and other climatic features such as the east atlantic western russia eawr pattern

advancements in the use of speleothems as climate archives abstract speleothems have become a cornerstone of the approach to better understanding earth s climatic teleconnections due to their precise absolute chronologies their continuous or semicontinuous deposition and their global terrestrial distribution we review the last decade of speleothem related research building off a similar review by mcdermott 2004 in three themes i investigation of global teleconnections using speleothem based climate reconstructions ii refinement of climate interpretations from speleothem proxies through cave monitoring and iii novel technical methods of speleothem based climate reconstructions speleothem records have enabled critical insight into the response of global hydroclimate to large climate changes this includes the relevant forcings and sequence of climatic responses involved in glacial terminations and recognition of a global monsoon response to climate changes on orbital and millennial time scales we review advancements in understanding of the processes that control speleothem 13 c values and introduce the idea of a direct atmospheric pco 2 influence we discuss progress in understanding kinetic isotope fractionation which with further advances may help quantify paleoclimate changes despite non equilibrium formation of speleothems this feeds into the potential of proxy system modeling to consider climatic hydrological and biogeochemical processes with the objective of quantitatively interpreting speleothem proxies finally we provide an overview of emerging speleothem proxies and novel approaches using existing proxies most recently technical advancements made in the measurement of fluid inclusions are now yielding reliable determinations of paleotemperatures

north atlantic influence on holocene flooding in the southern greater caucasus in the context of global climate change flooding becomes an increasingly serious threat to modern societies and future flooding can only be understood using long term geological flood records als

shear wave structure in the northeastern tibetan plateau from rayleigh wave tomography 1 the northeastern tibetan plateau has undergone active shortening due to the india asia collision and has been an ideal place for studying the growth of the plateau to reveal deep structure that is responsible for geological observations in ne tibet we have constructed a 3 d shear wave velocity model from rayleigh waves recorded by 36 stations in the northeast tibetan plateau seismic experiment first the two plane wave tomography method was applied to compute the average and 2 d variations of phase velocities in a period range of 20 to 100 s then 1 d and 3 d shear wave velocity models were developed from the obtained rayleigh wave dispersions the entire region is characterized by a weak upper mantle with a relatively thin lithosphere of 80 100 km thick this observation helps to explain the active deformation at the kunlun mountains and the qinling orogen in ne tibet relative low velocity anomalies appear along and to the south of the kunlun fault kf in contrast to high velocity anomalies in the north and northeast one pronounced slow anomaly centered at 120 km depth is imaged right beneath the restraining bend of the kunlun fault which might be a northern extension of the large scale slow anomaly to the south of the fault we interpret it as a local feature due to its large magnitude and coincidence with the restraining bend it is probably related to anomalously high temperature and associated partial melting resulted from localized asthenosphere upwelling after the delamination of a thick lithosphere root the formation of the thick lithosphere root would require coherent shortening in the crust and mantle lithosphere caused by local compression due to the bend of the strike slip fault indicating that the kunlun fault is probably on lithosphere scale and has played an important role in accommodating the eastward extrusion of the tibetan plateau

planktonic foraminiferal faunal and stable isotopic indices of upwelling a sediment trap study in the san pedro basin southern california bight

persistent positive north atlantic oscillation mode dominated the medieval climate anomaly the medieval climate anomaly mca was the most recent pre industrial era warm interval of european climate yet its driving mechanisms remain uncertain we present here a 947 year long multidecadal north atlantic oscillation nao reconstruction and find a persistent positive nao during the mca supplementary reconstructions based on climate model results and proxy data indicate a clear shift to weaker nao conditions into the little ice age lia globally distributed proxy data suggest that this nao shift is one aspect of a global mca lia climate transition that probably was coupled to prevailing la nina like conditions amplified by an intensified atlantic meridional overturning circulation during the mca

black carbon traces of human activities in stalagmites from turkey abstract speleothems are recognized as sensitive recorders of climatic fluctuations in the past and provide precisely dated and highly resolved environmental records however their potential as an archaeological archive is not fully acknowledged yet here we present several stalagmites containing soot and charcoal layers from various caves in turkey and provide evidence that these black carbon layers are directly related to human activity the archaeological artefacts found in tabak and kocain caves in sw turkey support the linkage between soot and charcoal layers existence and human activity in the caves for this study we focus on stalagmites from tabak and kocain cave to explore the age and nature of the soot and charcoal layers within stalagmites ta 9 ta 10 and ko 1 uranium series dating scanning electron microscope sem and thin section analyses were performed the episodic soot and charcoal deposition in stalagmites ta 9 and ta 10 occurred between 7424 225 yr bp and 6670 218 yr bp while the soot and charcoal layers in stalagmite ko 1 formed between 2830 189 yr bp and 470 56 yr bp in combination with the archaeological inventory in tabak cave the soot and charcoal layers within stalagmites ta 9 and ta 10 show that the cave was used repeatedly as a burial site during chalcolithic period in kocain cave was also used repeatedly between the iron age and medieval period most likely for ritual activities and for providing animals with water from a small spring in the entrance to the cave the soot and charcoal layers within stalagmites from turkey prove that speleothems are also important as archaeological archives

vertical distribution and isotopic fractionation of living planktonic foraminifera from the panama basin a model1 2 which explains the vertical and seasonal distribution of planktonic foraminifera was developed using data from the western north atlantic and is comprised of three tenets 1 the conditions in the photic zone upper 80 100 m exclusively dictate planktonic foraminifera species composition and abundance throughout the water column 2 species are vertically stratified within the photic zone according to their temperature preference depth distribution according to temperature preference has been proposed by several authors3 based on isotope analyses of sediments due to seasonal temperature variations seasonal variations in the 18o composition of seawater and species specific isotope fractionation rigorous proof of this hypothesis cannot be provided from sediment analyses alone 3 the chlorophyll maximum is a major food source zone which is preferentially exploited by foraminifera our data from the panama basin which are presented here are confirmation of this model the panama basin in the eastern equatorial pacific which has a shallow and steep thermocline was sampled for living planktonic foraminifera a multiple opening closing net and environmental sensing system mocness 4 was used to collect 13 sets of eight vertically stratified oblique samples we report here the quantitative distribution and stable isotopic composition of planktonic foraminifera from four mocness tows taken over 5 days during august 1979 rv knorr cruise 73 at 5 20 n 8 50 w each tow consisted of eight samples which integrated 12 5 m intervals from 0 to 100 m for moc 126 25 m intervals from 0 to 200 m for moc 127 100 150 m intervals from 0 to 1 000 m on moc 128 and 250 m intervals from 0 to 2 000 m on moc 131

speleothem evidence for late holocene climate variability and floods in southern greece abstract we present stable isotope data 18o 13c from a detrital rich stalagmite from kapsia cave the peloponnese greece the cave is rich in archeological remains and there are reasons to believe that flooding of the cave has directly affected humans using the cave using a combination of u th and 14c dating to constrain a site specific correction factor for 232th 238u detrital molar ratio a linear age model was constructed the age model shows that the stalagmite grew during the period from ca 950 bc to ca ad 830 the stable oxygen record from kapsia indicates cyclical changes of close to 500 yr in precipitation amount with rapid shifts towards wetter conditions followed by slowly developing aridity superimposed on this signal wetter conditions are inferred around 850 700 500 and 400 100 bc and around ad 160 300 and ad 770 and driest conditions are inferred to have occurred around 450 bc ad 100 150 and ad 650 detrital horizons in the stalagmite indicate that three major floods took place in the cave at 500 bc 70 bc and ad 450 the stable carbon isotope record reflects changes in biological activity being a result of both climate and human activities

five hundred years of gridded high resolution precipitation reconstructions over europe and the connection to large scale circulation we present seasonal precipitation reconstructions for european land areas 30 w to 40 e 30 71 n given on a 0 5 0 5 resolved grid covering the period 1500 1900 together with gridded reanalysis from 1901 to 2000 mitchell and jones 2005 principal component regression techniques were applied to develop this dataset a large variety of long instrumental precipitation series precipitation indices based on documentary evidence and natural proxies tree ring chronologies ice cores corals and a speleothem that are sensitive to precipitation signals were used as predictors transfer functions were derived over the 1901 1983 calibration period and applied to 1500 1900 in order to reconstruct the large scale precipitation fields over europe the performance quality estimation based on unresolved variance within the calibration period of the reconstructions varies over centuries seasons and space highest reconstructive skill was found for winter over central europe and the iberian peninsula precipitation variability over the last half millennium reveals both large interannual and decadal fluctuations applying running correlations we found major non stationarities in the relation between large scale circulation and regional precipitation for several periods during the last 500 years we identified key atmospheric modes for southern spain northern morocco and central europe as representations of two precipitation regimes using scaled composite analysis we show that precipitation extremes over central europe and southern spain are linked to distinct pressure patterns due to its high spatial and temporal resolution this dataset allows detailed studies of regional precipitation variability for all seasons impact studies on different time and space scales comparisons with high resolution climate models as well as analysis of connections with regional temperature reconstructions

perovskite u pb and sr nd isotopic perspectives on melilitite magmatism and outward growth of the tibetan plateau mantle derived alkaline magmatism along major strike slip faults provides unique insights into the lateral growth of the tibetan plateau here we use the geochemistry of perovskites from the west qinling melilitite to probe into the nature and dynamics of sub lithospheric mantle beneath the northeastern tibetan plateau the texture and chemical composition of perovskites indicate their early crystallization from a co2 rich melilitite magma most perovskite crystals have moderately depleted sr nd isotopic compositions whereas a few grains exhibit high 87sr 86sri and low end t together with the bulk rock geochemistry of the melilitite the perovskite sr nd isotope data imply that the primary magma parental to the melilitite was most likely derived from seafloor subduction modified asthenosphere and underwent interaction with lithospheric mantle during ascent in situ u pb dating of the perovskites demonstrates the temporal correlation between the melilitite magmatism and kunlun strike slip faulting in the early miocene these findings indicate the fundamental role of india asia convergence in driving outward plateau growth through strike slip extrusion and in reactivating long lived lithospheric zones of weakness for evacuating low volume asthenospheric melts

modelling karst vadose zone hydrology and its relevance for paleoclimate reconstruction abstract understanding past climatic changes allows us to better understand how our planet will evolve in the future one important source of information on paleoclimate is the analysis of speleothems that develop in karst caves and conduits due to the dissolution and precipitation of calcite however there are many uncertainties in paleoclimatic reconstruction with speleothems one of them being hydrological variability up to now only few studies have considered the impact of hydrological variability on speleothem formation and composition this review paper will provide an introduction to hydrological processes that have the potential to affect speleothem composition and the hydrological modelling approaches that are able to account for them it presents the current state of knowledge on paleoclimatic reconstruction using speleothems and shows that many important flow and transport processes have not yet been included in the interpretation of these archives mostly due to a lack of field information to parametrize them possible directions of future research efforts therefore include a better exploration of karst vadose zone processes and new approaches to incorporate this information into simulation models finally we foresee the exciting advances in reconstructing paleohydrology using karst hydrology models combined with speleothem growth rate and geochemical composition to understand how past climate changes affected the hydrological cycle and water availability

oblique stepwise rise and growth of the tibet plateau two end member models of how the high elevations in tibet formed are i continuous thickening and widespread viscous flow of the crust and mantle of the entire plateau and ii time dependent localized shear between coherent lithospheric blocks recent studies of cenozoic deformation magmatism and seismic structure lend support to the latter since india collided with asia 55 million years ago the rise of the high tibetan plateau likely occurred in three main steps by successive growth and uplift of 300 to 500 kilometer wide crustal thrust wedges the crust thickened while the mantle decoupled beneath gently dipping shear zones did not sediment infilling bathtub like of dammed intermontane basins formed flat high plains at each step the existence of magmatic belts younging northward implies that slabs of asian mantle subducted one after another under ranges north of the himalayas subduction was oblique and accompanied by extrusion along the left lateral strike slip faults that slice tibet s east side these mechanisms akin to plate tectonics hidden by thickening crust with slip partitioning account for the dominant growth of the tibet plateau toward the east and northeast

speleothem isotopic evidence of winter rainfall variability in northeast turkey between 77 and 6 ka an oxygen isotope record from a stalagmite that grew between 77 ka and 6 ka in northeast turkey contains both a strong precessional signal and sub orbital oscillations similar to those in greenland ice cores and chinese speleothem records of monsoon intensity fluid inclusion evidence of a negative shift in the isotopic composition of dripwater during the lateglacial supports interpretation of the isotope curve as an insolation forced record of changes in rainfall seasonality the high amplitude millennial scale fluctuations are caused by rapid changes in rainfall seasonality and or switching of moisture source areas both of which are associated with the stadial interstadial climatic oscillations linked to the changing modes of the north atlantic meridional overturning circulation moc winter rainfall maxima in northeast turkey coincide with interstadial conditions in greenland and with periods of intensified asian monsoon activity the isotopic shifts in the record are in antiphase with and are generally much larger in amplitude than published data from stalagmites in northwest turkey most likely because of differing moisture source areas carbon isotope ratios are probably kinetically enriched by partial degassing of seepage water in the epikarst but although often difficult to decypher particularly during marine isotope stage mis 2 broadly support the interpretations of the oxygen data

a high resolution late holocene lake isotope record from turkey and links to north atlantic and monsoon climate a high resolution proxy record of precipitation and evaporation variability through the past 1700 yr from 18o analysis of a varved lake sequence from central turkey shows rapid shifts between dry periods ad 300 500 and ad 1400 1950 and wetter intervals ad 560 750 and ad 1000 1350 changes are consistent with changes in instrumental and proxy records of the indian monsoon dry summers in the eastern mediterranean being associated with periods of enhanced monsoon rainfall in addition major shifts in the record are coherent with changes in north atlantic winter climate with cold wet periods in the alps occurring at times of dry turkish climate

may june precipitation reconstruction of southwestern anatolia turkey during the last 900 years from tree rings abstract a may june precipitation reconstruction ad 1097 2000 has been developed for southwestern anatolia in turkey the longest reported to date in this region the reconstruction was derived from a regional juniperus excelsa chronology that was built from material sampled at four sites in the antalya and mersin districts the regional tree ring chronology accounts for 51 of the variance of instrumentally observed may june precipitation the years ad 1518 to 1587 are the most humid period in the reconstruction coinciding with a major shift in european climate the driest 70 year period in the reconstruction is ad 1195 to 1264 the period ad 1591 1660 represents the third driest and was characterized by instability climatically politically and socially in anatolia

paleohydrographic changes in the somali basin 5 n upwelling and equatorial areas during the last 160 kyr based on correspondence analysis of foraminiferal and radiolarian assemblages this study documents the biological signatures impressed upon the sedimentary record underlying both the 5 n upwelling system of the somali current and the equatorial area of the somali basin out of the upwelling influence the evolution of these two distinct hydrographic systems is compared for the last 160 kyr correspondence and cluster analyses are performed on combined radiolarian and planktonic foraminiferal quantitative data in order to study the changes of the planktonic assemblages through time and space the upwelling radiolarian index uri is used as a productivity proxy the water temperature and hydrographic structure of the upper water masses appear to be the major factors controlling the distribution patterns of the fauna the relative abundances of three groups of foraminifera cold water form dextral n pachyderma mixed layer dwellers g trilobus g ruber g sacculifer g conglobatus and g glutinata and thermocline dwellers g menardii g tumida n dutertrei g crassaformis and p obliquiloculata follow distinct evolutionary patterns at the two sites during the last 160 kyr at the equatorial site core md 85668 downcore fluctuations in the relative abundances of the three groups are closely related to the glacial interglacial cyclicity and provide some insights into the interpretation of hydrographic changes the dominance of the mixed layer foraminifera at the transition intervals between isotope stages 6 5 and 2 1 combined with weak uri values is thought to reflect the reorganization of the oceanographic circulation these short term events with a duration of 5000 year could be related to the rapid inflow of oxygen depleted water through the indonesian straits as a result of sea level rise during deglaciation underneath the 5 n gyre core md 85674 the response to global climatic changes is overprinted by the regional effect of the somalian upwelling which has been persistent over the last 160 kyr

late quaternary paleoceanography of the south china sea glacial interglacial contrasts in an enclosed basin the sea surface paleotemperature of the south china sea scs is estimated quantitatively based on the quantitative analysis of planktonic foraminiferal faunas recovered from piston cores v36 06 3 v36 06 5 and so49 kl8 on the northern continental slope the results lead to a reconstruction of the history of paleocirculation patterns during the last 200 000 years the postglacial and interglacial transbasinal circulation pattern was replaced by a semienclosed basin flow pattern during glacial episodes lowered sea level transformed the scs into a semienclosed basin with the only passageway to the open ocean in its northeastern corner the east asian monsoon which governs circulation patterns in the scs both today and during the late quaternary created both clockwise summer and counterclockwise winter surface gyres during glacials the inflow of tropical surface water masses from both the pacific and indian oceans decreased or was completely cut off from this marginal sea causing a greater decrease in glacial sea surface temperature than in the open ocean of the same latitude inferred increased influence of pacific temperate waters and decreased influence of tropical subtropical waters are confirmed by changes in the planktonic foraminiferal assemblages glacial interglacial fluctuation in sea surface temperature sst 6 8 9 3 c for winter and 2 3 c for summer as well as the seasonality 4 6 c for postglacial and interglacials and 9 10 c for glacials are much greater than the adjacent open western pacific reflecting the amplification of the climatic signal in the marginal sea

reconstruction of cave air temperature based on surface atmosphere temperature and vegetation changes implications for speleothem palaeoclimate records abstract cave temperature is a parameter of major importance for palaeoclimate studies based on speleothems since most proxies used are temperature dependent the general assumption that cave temperature reflects the mean annual surface atmosphere temperature sat over the cave is based on a limited number of specific studies and detailed mechanisms supporting this link are not properly described eagle cave in spain was used to understand the detailed mechanisms connecting sat and cave temperature a monitoring programme conducted from 2009 to 2011 allows the characterization of the thermal dynamics in the cave air in the studied karstic environment thermal conduction is the main mechanism responsible for transferring the ground temperature signal to the cave the calculated thermal diffusion coefficient is 0 756 10 6 0 013 m 2 s 1 the sat signal is recorded at the cave with a delay ranging from 3 to 11 yr depending on the thickness of the bedrock over the ceiling 5 18 m a cave cooling of 2 c has been recorded since mid 1970s when cave temperature measurements were made the application of a model exclusively based on thermal conduction of sat does not reproduce the observed thermal changes however vegetation cover over the cave was modified dramatically during recent decades this impacts ground temperature due to the changes in exposure to insolation and the modification of soil properties which is eventually recorded in the cave the incorporation of changes in vegetation cover in the model provides a realistic thermal reconstruction the impact of vegetation cover was much more significant than sat in order to explain the large thermal change in the cave over past decades thus the cooling in eagle cave during past decades is mainly controlled by a variable decoupling from mean annual sat as a result of the afforestation over the cave the effect of this thermal decoupling on speleothem 18 o records is potentially significant and should be considered when performing accurate palaeoclimate reconstructions

the history of coastal upwelling off peru 11 s odp leg 112 site 680b over the past 650 000 years the coarse sediment fraction 63 m and benthic foraminiferal composition of quaternary sediment cores from odp leg 112 hole 680b 252 5 m water depth were sampled from the upwelling area off peru high resolution oxygen isotope stratigraphy based on analyses of the benthic foraminifera bolivina seminuda allows a detailed reconstruction of the upwelling history since oxygen isotope stage 16 variations in the relative abundances of the benthic foraminiferal species nonionella auris bolivina costata and bolivina seminuda document changes in fertility which were found to be enhanced during interglacial stages 1 3 5 7 9 and 11 generally bioturbated sediments are dominated by the genera cassidulina epistominella gyroidina trifarina and valvulineria these benthic foraminifera are members of the undercurrent fauna which is commonly associated with sediments that have a high terrigenous detrital component and a low organic carbon content 6 ml l o2 the entire core interval investigated in hole 680b appears to have been affected by the peruvian undercurrent generally undercurrent dominated sections were found to correspond with glacial oxygen isotope stages

peruvian coastal upwelling late quaternary productivity changes revealed by diatoms a transfer function pdu 1 relating modern marine diatom sediment surface assemblages to a 10 year averaged surface water primary productivity map spanning a range of 0 1 1 0 g c m2 day is used to interpret downcore variation in productivity at three sites site 680 681 and 686 of odp leg 112 off peru variation in coastal upwelling determined by the transfer function method and by qualitative assessment using smear slides from each site were staked into one composite record for the last 400 000 years this record revealed the following productivity at 11 and 13 5 s was highly variable during the last 400 000 years with the strongest coastal upwelling phases occurring during the following oxygen isotope stages middle of 1 upper part of 3 lower part of 5 the 67 and 78 transition lower part of 8 upper and lower part of 9 and middle part of 11 significant decreases in upwelling occurred during the following oxygen isotope stages lower part of 1 4 upper part of 5 upper part of 7 upper part of 9 the 1011 transition and the upper part of 11 the overall decreases and increases in paleoproductivity are not in phase with the general glacial interglacial cycles the variability of coastal upwelling is more complex and largest swings in the magnitude of paleoproductivity seem to occur across oxygen isotope stage boundaries the periods of highest paleoproductivity are characterized by excellent diatom assemblage preservation high abundance of skeletonema and delphineis and varved or finely laminated sediments periods when paleoproductivity was weaker on the other hand are characterized by bioturbated sediments poor diatom preservation and high abundance of azpeitzia coscinodiscus nodulifer and pseudoeunotia doliolus

low temperature thermochronometry along the kunlun and haiyuan faults ne tibetan plateau evidence for kinematic change during late stage orogenesis the tibetan plateau is a prime example of a collisional orogen with widespread strike slip faults whose age and tectonic significance remain controversial we present new low temperature thermochronometry to date periods of exhumation associated with kunlun and haiyuan faulting two major strike slip faults within the northeastern margin of tibet apatite and zircon u th he and apatite fission track ages which record exhumation from 2 to 6 km crustal depths provide minimum bounds on fault timing results from kunlun samples show increased exhumation rates along the western fault segment at circa 12 8 ma with a possible earlier phase of motion from 30 20 ma along the central fault segment at circa 20 15 ma and along the eastern fault segment at circa 8 5 ma combined with previous studies our results suggest that motion along the haiyuan fault may have occurred as early as 15 ma along the western central fault segment before initiating at least by 10 8 ma along the eastern fault tip we relate an 250 km wide zone of transpressional shear to synchronous kunlun and haiyuan fault motion and suggest that the present day configuration of active faults along the northeastern margin of tibet was likely established since middle miocene time we interpret the onset of transpression to relate to the progressive confinement of tibet against rigid crustal blocks to the north and expansion of crustal thickening to the east during the later stages of orogen development

applications of stalagmite laminae to paleoclimate reconstructions comparison with dendrochronology climatology abstract laminated stalagmites observed in either ultra violet or visible light or recognized via trace elements are now widely recognized as a common deposition form annually laminated stalagmites should be expected in caves which have an overlying climate that has a strong seasonality similar climate zones to where trees grow with distinct annual rings continuous laminated stalagmite chronologies up to several thousand years should be expected where some mixing of stored water occurs such stalagmites can be used to reconstruct climate particularly through variations in lamina width such climate records would be relatively damped by mixing of event water with stored groundwater constraining the amount of high frequency climate signals contained in the stalagmite but relatively long continuous lamina sequences permit the preservation of low frequency centennial scale climate signals this contrasts with numerous tree ring climate records which are frequently limited in preserving multi centennial trends due to the necessary removal of age related noise from relatively short tree segments laminated stalagmites and tree rings should therefore to some degree provide complementary climate information appropriate methods for compiling stalagmite layer chronologies and climatologies are presented

a 500 yr speleothem derived reconstruction of late autumn winter precipitation northeast turkey a verified instrumental calibration of annually resolved 18o for a stalagmite from gumushane in northeast turkey is presented and cross validated using a leave one out technique the amount of late autumn to winter precipitation is negatively correlated with stalagmite 18o between ad 1938 and 2004 the observed relationship is extrapolated back to ad 1500 leading to the first long winter precipitation reconstruction for this region modern day october to january precipitation is linked to pressure fields in western russia anomalously lower reconstructed rainfall is recorded in ad 1540 1560 at which time higher pressure over the caspian sea region is inferred