triple oxygen isotope equilibrium fractionation between carbon dioxide and water abstract the growing number of recent high precision triple oxygen isotope data of water and atmospheric gases requires the reinvestigation of the major isotope fractionation processes between the hydro bio and atmosphere here we present the experimental triple oxygen isotope fractionation factor between co 2 gas and water in the temperature range between 2 and 37 c we have determined the triple oxygen isotope fractionation factor ln 17 ln 18 for co 2 water equilibrium and found that co2 water 0 522 0 002 t 0 95 sem no temperature dependence was resolved knowledge on the triple oxygen isotope equilibrium fractionation between co 2 and water is crucial for estimating the triple oxygen isotope composition of tropospheric co 2 model predictions combined with high precision 17 o analysis of tropospheric co 2 might reveal new information on biosphere atmosphere interactions or the influx of anomalous stratospheric co 2

exploring the usability of isotopically anomalous oxygen in bones and teeth as paleo co2 barometer fluctuations in atmospheric pco2pco2 may have played the key role in global climate throughout earth s history for the quantification of past variations in atmospheric pco2pco2 several geological proxy approaches and geochemical models have been developed here we evaluate a new co2 proxy approach that is based on the triple oxygen isotope composition 16o 17o 18o of skeletal apatite of terrestrial mammals our approach utilizes the relation between an anomaly in 17o of tropospheric air o2 and atmospheric pco2pco2 the anomaly is transferred from inhaled air o2 to skeletal apatite of mammals hence triple oxygen isotope data of mammalian bioapatite provide information regarding pco2pco2 during the animal s lifetime the approach was calibrated with a detailed mass balance model that was verified by analyses on a set of recent mammals we evaluate the potential of this new independent terrestrial paleo co2 proxy in a case study including eocene to miocene samples the present investigation provides promising results that are in good agreement with existing proxy and model data the uncertainty intrinsic to the proxy is mainly due to uncertainties in physiological parameters

uplift of the western altiplano plateau evidence from the precordillera between 20 and 21 s northern chile 1 we present a quantitative reconstruction of uplift of the western flank of the altiplano plateau central andes one of the largest monoclines on the earth on the basis of an analysis of tectonic structures syntectonic deposits and geophysical data uplift occurred on a west vergent slowly propagating system of high angle reverse faults merging into a joint detachment that ramps down to midcrustal levels below the plateau edge the upper ramps determine local fold geometries while the lower ramp controls large scale surface tilting and uplift at 20 s this fault system was active between 30 ma and 5 10 ma with maximum shortening rates of 0 22 mm yr between 17 and 10 ma it generated some 2600 m of surface uplift with only minor shortening of 3000 m its activity was largely synchronous to eruption of large volume ignimbrites from a midcrustal source geophysical data indicate that the fault system localized deformation at the boundary between a cool strong forearc crust and a presumably fluid rich and or partially molten zone underneath the plateau area the systematic relation between crustal melting and shortening with uplift at the western plateau margin can be traced along most of the plateau flank with a stepwise decrease in age of deformation and magmatism toward the south indicating discontinuous addition of plateau segments crustal thickening to as much as 70 km from westward underthrusting in the back arc parts of the plateau isostatically compensated the tectonic surface uplift and monocline formation with respect to a stable forearc which only reacted with minor tilting

standardizing the reporting of δʹ17o data from high precision oxygen triple isotope ratio measurements of silicate rocks and minerals abstract accurate and precise 17o data are important for quantifying and understanding processes responsible for variations of oxygen triple isotope ratios in nature without universally agreed numerical values of rl and rl in the definition 17o ln 1 17o rlln 1 18o rl however as is currently the situation for measurements on rocks and minerals reported 17o data may not be directly comparable furthermore the accuracy of 17o measurements is linked to calibration at the ppm level of individual laboratory s working standard o2 relative to the vsmow water reference or to the vsmow slap scale whereas few laboratories have the facility to make high precision 17o and 18o measurements on silicates and waters both points may be addressed by defining a reference line from measurements of a pair of silicates which differ substantially in oxygen isotopic composition comparable to the difference between vsmow and slap rather than by assigning rl and rl values arbitrarily the resulting reference line has no physical significance however because 17o values reported relative to it are independent of the calibration of the working standard o2 this greatly facilitates 17o reproducibility and comparability we propose silicate standards for this purpose and report comparative measurements from two institutions of the respective 17o and 18o values relative to vsmow together with 17o data relative to various assigned reference lines we also report 17o measurements of uwg 2 garnet san carlos olivine and nbs 28 quartz relative to our reference line the proposed standards are 1 krs khitostrov rock standard 18o 25 20 which consists of sintered fine grained constituents primarily garnet of a very low 18o amphibolite grade palaeoproterozoic rock from khitostrov karelia russia 2 skfs stevns klint flint standard 18o 33 93 consisting of thermally dehydrated grains of a high 18o nodule of flint sampled from just below the exposed cretaceous palaeogene boundary at stevns klint southeast zealand island denmark both silicates fluorinate readily using standard laser assisted procedures and the associated low blanks allow for overnight pre treatment small quantities of these materials may be supplied on request for standardizing 17o measurements of silicate rocks and minerals according to the proposed procedure

the triple oxygen isotope composition of the earth mantle and understanding δo17 variations in terrestrial rocks and minerals abstract it has been shown in numerous studies that terrestrial rocks and minerals fall on a line with slope 0 52 in a o 17 vs o 18 diagram in this study we present new data on the triple isotope composition of the earth mantle crustal materials and low t aqueous precipitates crustal materials show distinct variations in o 17 suggesting that the concept of a single terrestrial mass fractionation is invalid on small scale observable variations in individual fractionation slopes are interpreted as temperature effects we show that the earth mantle is isotopically homogeneous and confirm the recent finding that the earth mantle has a negative o 17 the difference in o 18 and o 17 between seawater and oceanic crust is discussed with respect to the effects of low and high temperature water rock interaction

triple oxygen isotopes in biogenic and sedimentary carbonates abstract the 17 o anomaly 17 o of natural waters has been shown to be sensitive to evaporation in a way analogous to deuterium excess with evaporated bodies of water e g leaf waters lake waters animal body waters tending to have lower 17 o than primary meteoric waters in animal body water 17 o relates to the intake of evaporated waters evaporative effluxes of water and the 17 o value of atmospheric o 2 which itself carries signatures of global carbon cycling and photochemical reactions in the stratosphere carbonates have the potential to record the triple oxygen isotope compositions of parent waters allowing reconstruction of past water compositions but such investigations have awaited development of methods for high precision measurement of 17 o of carbonate we describe optimized methods based on a sequential acid digestion reduction fluorination approach that yield 17 o data with the high precision 0 010 1 needed to resolve subtle environmental signals we report the first high precision 17 o dataset for terrestrial carbonates focusing on vertebrate biogenic carbonates and soil carbonates but also including marine invertebrates and high temperature carbonates we determine apparent three isotope fractionation factors between the o 2 analyte derived from carbonate and the parent waters of the carbonate these in combination with appropriate temperature estimates from clumped isotope thermometry or known or estimated body temperatures are used to calculate the 18 o and 17 o of parent waters the clearest pattern to emerge is the strong 17 o depletion in avian dinosaurian and mammalian body water from analyses of eggshell and tooth enamel relative to meteoric waters following expected influences of evaporated water e g leaf water and atmospheric o 2 on vertebrate body water parent waters of the soil carbonates studied here have 17 o values that are similar to or slightly lower than global precipitation our results suggest that 17 o will have useful application to paleoenvironmental studies of continental environments where the effects of evaporation are important and where vertebrate body water may record an isotopic signal of evaporated water sources and atmospheric oxygen

uplift of the western margin of the andean plateau revealed from canyon incision history southern peru we explore canyon incision history of the western margin of the andean altiplano puna plateau in the central andes as a proxy for surface uplift u th he apatite data show rapid cooling beginning at ca 9 ma and continuing to ca 5 1 ma in response to incision a minimum of 1 0 km of incision took place during that interval the youngest apatite date and a volcanic fl ow perched 125 m above the present valley fl oor dated at 2 261 0 046 ma 40 ar 39 ar show that an additional 1 4 km of incision occurred between ca 5 1 and 2 3 ma thus we infer that a total of at least 2 4 km or 75 of the present canyon depth was incised after ca 9 ma u th he zircon data collected along the same transect imply that the western margin of the plateau was warped upward into its present monoclinal form rather than uplift being accommodated on major surface breaking faults

oxygen isotopic homogeneity of the earth new evidence abstract the two oxygen isotope ratios 18 o 16 o and 17 o 16 o were analyzed in precambrian 3 5 gy and modern cherts and in mantle derived lavas all samples exhibit oxygen isotopic compositions consistent with mass dependent isotopic fractionation from a single reservoir and thus suggest that 3 5 gy ago the earth was already a well mixed body these results would therefore not support models of ocean accretion by cometary impact later than 3 7 0 1 gy new measurements on lunar rocks confirm oxygen isotopic homogeneity of the earth moon system and thus suggests that the internal mixing of the two bodies pre dates their accretion the recent giant impact model used to explain how the moon was formed is also compatible with our results

rapid late miocene rise of the bolivian altiplano evidence for removal of mantle lithosphere abstract the oxygen isotopic compositions of carbonates deposited in the northern altiplano demonstrate a rapid change in late miocene time which we attribute to an increase in elevation rainfall samples over an elevation transect adjacent to the altiplano of northern bolivia display a systematic decrease in mean annual 18 o values and define a local 18 o vs altitude gradient r gonfiantini m a roche j c olivry j c fontes g m zuppi the altitude effect on the isotopic composition of tropical rains chem geol 181 2001 147 167 which we apply to paleo meteoric water values determined from carbonates age constraints from magnetostragraphy and paleoelevation estimates suggest surface uplift of 2 5 to 3 5 km occurred between 10 3 ma and 6 8 0 4 ma when the altiplano rose to its current elevation only the removal of dense eclogitic lower crust and mantle lithosphere can generate a change of this magnitude and rapidity this change coincides with an 30 decrease in the rate of convergence between the south america and nazca plates and the propagation of deformation into the eastern subandean zone which we infer to have resulted from the increase in the force per unit length applied by the elevated andean plateau to the surrounding lowlands

plateau style accumulation of deformation southern altiplano 1 employing surface mapping of syntectonic sediments interpretation of industry reflection seismic profiles gravity data and isotopic age dating we reconstruct the tectonic evolution of the southern altiplano 20 22 s between the cordilleras defining its margins the southern altiplano crust was deformed between the late oligocene and the late miocene with two main shortening stages in the oligocene 33 27 ma and middle late miocene 19 8 ma that succeeded eocene onset of shortening at the protoplateau margins shortening rates in the southern altiplano ranged between 1 and 4 7 mm yr with maximum rates in the late miocene summing rates for the southern altiplano and the eastern cordillera we observe an increase from eocene times to the late oligocene to some 8 mm yr followed by fluctuation around this value during the miocene prior to shutoff of deformation at 7 8 ma and transfer of active shortening to the sub andean fold and thrust belt shortening inverted early tertiary graben and half graben systems and was partitioned in three fault systems in the western central and eastern altiplano respectively the east vergent fault systems of the western and central altiplano were synchronously active with the west vergent altiplano west flank fault system from these data and from section balancing we infer a kinematically linked western altiplano thrust belt that accumulated a minimum of 65 km shortening evolution of this belt contrasts with the eastern cordillera which reached peak shortening rates 8 mm yr in between the above two stages hence local shortening rates fluctuated across the plateau superimposed on a general trend of increasing bulk rate with no trend of lateral propagation this observation is repeated at the shorter length and time scales of individual growth structures that show evidence for periods of enhanced local rates at a timescale of 1 3 myr we interpret this irregular pattern of deformation to reflect a plateau style of shortening related to a self organized state of a weak crust in the central south american back arc with a fault network that fluctuated around the critical state of mechanical failure tuning of this state may have occurred by changes in plate kinematics during the paleogene initially reactivating crustal weak zones and by thermal weakening of the crust with active magmatism mainly in the neogene stage

clumped isotope geochemistry the study of naturally occurring multiply substituted isotopologues clumped isotope geochemistry is concerned with the state of ordering of rare isotopes in natural materials that is it examines the extent to which rare isotopes d 13 c 15 n 18 o etc bond with or near each other rather than with the sea of light isotopes in which they swim abundances of isotopic clumps in natural materials are influenced by a wide variety of factors in most cases their concentrations approach within ca 1 relative the amount expected for a random distribution of isotopes deviations from this stochastic distribution result from enhanced thermodynamic stability of heavy isotope clumps slower kinetics of reactions requiring the breakage of bonds between heavy isotopes the mass dependence of diffusive and thermo gravitational fractionations mixing between components that differ from one another in bulk isotopic composition biochemical and photochemical fractionations that may reflect combinations of these simpler physical mechanisms and in some cases other processes we do not yet understand although clumped isotope geochemistry is a young field several seemingly promising applications have already emerged most importantly it appears that proportions of 13 c 18 o bonds in carbonate minerals are sensitive to their growth temperatures independent of bulk isotopic composition thus clumped isotope analysis of ancient carbonates can be used as a quantitative paleothermometer that requires no assumptions about the 18 o of waters from which carbonates grew this approach has been used to reconstruct marine temperatures across the phanerozoic reaching back to the silurian terrestrial ground temperatures across the cenozoic thermal histories of aqueously altered meteorites among other applications clumped isotope geochemistry is also placing new constraints on the atmospheric budget and stratospheric photochemistry of co 2 and should be capable of placing analogous new constraints on the budgets of other atmospheric gases finally this field could be extended to encompass sulfates volatile hydrocarbons organic moieties and other materials

variations of 17o 16o and 18o 16o in meteoric waters the variations of d 17 o and d 18 o in recent meteoric waters and in ice cores have proven to be an important tool for investigating the present and past hydrologic cycle in order to close significant information gaps in the present distribution ofd 17 o and d 18 o of meteoric water we have run precise measurements with respect to vsmow on samples distributed globally from low to high latitudes based on the new and existing data we present the global meteoric water line gmwl ford 17 o andd 18 o as ln d 17 o 1 0 528 ln d 18 o 1 0 000033 r 2 0 99999 in addition to meteoric water we carried out the first measurements of seawater from the pacific and atlantic oceans with respect to vsmow the obtained results show that the slope of the trend line ln d 17 o 1 vs ln d 18 o 1 of seawater samples is 0 528 the same as for meteoric water but the regression intercept is 5 per meg thus the positive intercept in the gmwl indicates an excess of 17 o in meteoric waters with respect to the ocean an excess or depletion of 17 o in water is defined as 17 o excess ln d 17 o 1 0 528 d 18 o 1 most meteoric water samples have positive 17 o excess of varying magnitudes with an average of 37 per meg with respect to vsmow we explain how these positive values originate from evaporation of sea water into marine air which is undersaturated in water vapor and how subsequent increase of 17 o excess occurs when atmospheric vapor condenses to form liquid and solid precipitation we also clarify the effect of excessive evaporation on 17 o excess finally based on the new results on 17 o excess of seawater we recalculated the relationship of d 17 o vs d 18 o in vapor diffusion in air as 18 adiff 1 0096

geology and geochemistry of arenite quartzwacke from the late archaean sandur schist belt implications for provenance and accretion processes abstract detailed geological petrological and geochemical studies have been carried out on an arenite quartzwacke suite of rocks constituting a part of the late archaean sandur schist belt in dharwar craton southern india for understanding the nature of provenance for these sedimentary rocks the arenite quartzwacke consists of rounded to sub rounded and angular fragments of monocrystalline polycrystalline quartz quartzite and chert embedded in a fine grained matrix of quartz and sericite while arenites are more siliceous sio 2 80 92 wt the quartzwacke have relatively lower silica content ca 69 78 wt the arenites and quartzwackes have cia values ranging from 76 to 96 which suggest intense chemical weathering this is further corroborated by the positive correlation between al 2 o 3 and tio 2 in both these rock types the a cn k modeling of arenites and quartzwackes show evidence for addition of k 2 o during later metasomatic alteration in the a cnk fm ternary diagram all the samples plot along a mixing line between chlorite and sericite indicating alteration during k metasomatism and the presence of mafic rocks in the source the high concentration of hfse such as zr hf nb and ta and the trace element ratios th sc la sc th u and ce th in the arenite quartzwacke indicate a mixed provenance the rare earth element modeling of quartzwackes considering tonalite granite and amphibolite end members in the provenance suggests equal proportions of mafic and felsic end members a composition comprising of 25 tonalite 25 granite 50 amphibolite in the provenance appears to match with the observed range of ree patterns of quartzwackes the presence of higher proportions of granite in the provenance is evidenced by the large negative eu anomalies in these sediments field evidence and structural discordance suggest that the arenite quartzwacke suite is an allochthonous part of the sandur schist belt

origin of the high plateau in the central andes bolivia south america the bolivian altiplano in the central andes of south america is part of the second largest high plateau on earth it is an elongate region of subdued relief 1 2 105 km2 and 4 km above sea level bounded by the eastern cordillera and volcanic arc western cordillera here the crust is up to 75 km thick we describe the cenozoic geological evolution of this region using a revised chronostratigraphy and an analysis of the crustal and lithospheric structure crustal shortening and magmatic addition and locally sedimentation are the main mechanisms of cenozoic crustal thickening leading to nearly 4 km of surface uplift since the paleocene addition of mafic melts appears to be a first order mechanism of cenozoic crustal growth contributing 40 of the crustal thickening beneath the volcanic arc removal of the basal part of the lithosphere may have caused two episodes of widespread arc and behind arc mafic volcanism at 23 ma and 0 5 ma contributing to the surface uplift the altiplano originated as a sedimentary basin several hundred kilometers wide between the proto western cordillera and a narrow zone of uplift proto eastern cordillera farther east the latter zone formed by inversion of the center of a wide lacustrine or marine cretaceous paleocene basin close to sea level at 45 ma a thickness of 2 4 km of paleogene continental elastics accumulated in the proto altiplano basin subsequently in the oligocene we estimate that this region and the western margin of the eastern cordillera were technically shortened 22 65 km resulting in 9 km of average crustal thickening the altiplano basin was rejuvenated at 25 ma and subsequently flooded with up to 8 km thickness of detritus eroded from the uplifting eastern and western cordilleras between 25 and 5 ma folding and thrusting in the western margin of the eastern cordillera migrated westward into the center of the altiplano basin essentially terminating deposition except in local subbasins and accommodating 13 30 km of shortening and an estimated 7 km of average crustal thickening subsequently there has been strike slip deformation and limited local thrusting 5 km of shortening geomorphological and geochronological evidence for 1 5 2 km of surface uplift of this region since the late miocene suggests 14 km of lower crustal thickening beneath an essentially rigid lid and can be explained by 100 150 km of underthrusting of the brazilian shield and adjacent regions beneath the eastern margin of the central andes the present subdued relief in the altiplano may be a result of ductile flow in the lower crust and sedimentation and erosion in an internal drainage basin

comment on the triple oxygen isotope composition of the earth mantle and understanding δ17o variations in terrestrial rocks and minerals by pack and herwartz earth planet sci lett 390 2014 138 145

a quantitative evaluation of playfair s law and its use in testing long term stream erosion models playfair s law j playfair illustrations of the huttonian theory of the earth 1802 requires any two tributaries in a river network to lower at the same rate near their junction although this law holds exactly at the junction it is unclear how well it holds in the vicinity of the junction this issue has practical importance because playfair s law has been used to estimate parameters for detachment limited models of erosion if the incision rate of a stream is modelled as amsn where is an erodibility parameter a is the area drained by the stream and s is the local gradient of the channel then the ratio of the parameters m n can be estimated from junctions by assuming that playfair s law holds over the distance used to determine s for each tributary in this paper playfair s law and associated m n estimates are evaluated for simulated basins with constant and temporally varying uplift rates or baselevel lowering rates the results demonstrate that estimates of m n may be biased for basins with upward concave stream profiles because the local slope must be approximated with an average upstream slope in addition when uplift rate varies temporally knickpoints are shown to travel through the basins with constant vertical velocity because incision rates vary within the basin playfair s law only holds exactly at the junctions these effects are more important when slopes are measured over longer distances finally measurement techniques are presented which address these potential biases copyright 2001 john wiley sons ltd

triple oxygen isotope variations in sedimentary rocks relatively large 0 2 17 o anomalies in the geologic record have been used to recognize atmospheric processes such as photochemical reactions and to trace changes in the partial pressures of o 2 and co 2 in earth s atmosphere through time however recent oxygen isotope measurements of terrestrial rocks minerals and waters also reveal common smaller but statistically significant deviations from a single mass dependent fractionation line these subtle anomalies have been explained through differences in mass dependent isotopic fractionations for various equilibrium and kinetic mechanisms here we present triple oxygen isotope data on sedimentary silica and oxides including archean and phanerozoic cherts and iron formations the distribution of data reflects the mass fractionation laws of low temperature precipitation reactions during growth of authigenic minerals variation in 17 o of the waters from which sedimentary minerals precipitate and equilibrium exchange after initial authigenic formation we use these results to illustrate the potential for small mass dependent variations in 17 o values of sedimentary rocks to provide constraints on the environmental and climatic conditions in which they formed

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

late cenozoic deformation and uplift of the western flank of the altiplano evidence from the depositional tectonic and geomorphologic evolution and shallow seismic activity northern chile at 19 30 s 1 we analyze the west vergent thrust system wts along the western flank of the altiplano in northern chile 18 s 21 s in our study area 19 20 s 19 50 s the wts consists of three thrust propagation monocline folds flexures developing growth strata the relative uplift accommodated by the flexures is rapid between 26 and 8 ma 0 1 mm yr diminishing to 0 02 mm yr after 8 ma approximately 2000 m of relative surface uplift was accommodated by the flexures since the late oligocene sedimentological and geomorphological analysis shows that westward tilting of the forearc occurred after 10 ma coeval with the shifting of deformation from the altiplano to the sub andean zone where the underthrusting of the brazilian craton would have resulted in crustal thickening surface uplift in the orogen and westward ductile subcrustal flow forearc tilting is accommodated by east vergent thrusts ets issued from the benioff zone beneath the central depression emerging into the western cordillera contributing 500 1400 m of surface uplift the wts connects the ets in the brittle ductile crustal transition 25 km depth continuing farther east as the altiplano low velocity zone configuring the western altiplano as a crustal scale fault bend fold forearc tilting would be caused by westward ductile flow in the lower crust pushing the rigid forearc in the ets meanwhile between 19 s and 21 s the wts accommodates dextral strike slip and 3 km of n s shortening occurred in the coastal cordillera transcurrence and strain partitioning are probably the result of slight plate convergence obliquity strong coupling within the interplate zone westward continental concavity and high elevation opposing horizontal contraction