Core-top d18O values for ostracods and gastropods are close to calculated equilibrium values for calcite and aragonite, respectively
Core-top d18O values for ostracods and gastropods are close to calculated equilibrium values for calcite and aragonite, respectively
Core-top d18O values for ostracods and gastropods are close to calculated equilibrium values for calcite and aragonite, respectively
Comparison with lake water d18O
Comparison with lake water d18O
comparison of theoretical carbaontes precipitated from modern waters
Using Leng and Marshall's (2004) expression of Kim and O'Neil's (1997) equation, the surface sediment 18O value of 6.2? (core top taken in 1999) and 18O water of 8.1? (average between 1997 and 2001, Table 2) suggests precipitation temperatures of around 23C, higher than the measured mean annual air temperature of 18C.
our calculated [equilibium] d18OC values of ?12.7? are similar to core values from the last few hundred years, which lends support to the idea that the modern carbonates are precipitating in equilibrium.
isotopic values d18O of calcite precipitating in the surface waters of Zoi¿½ar Lake obtained from a buoy and anchor rope concretion growth show values (between ?2 to +1? vs V-PDB) coherent with calcite formation in isotopic equilibriumwith epilimnetic lake waters (+1 to + 6??18Owater (V-SMOW))
Comparison with lake water d18O
Unfortunately, neither of these cellulose-inferred lakewater d18O records extends to the present, which precludes direct linking with time series of modern lakewater d18O measurements
modern d18O.lakewater and d18O.calcite identical within error
The isotopic composition of this calcite [endogenic calcite in macrophyte coatings] is approximately in equilibrium with lake waters,
Australian ostracods precipitate calcite with approximately an 0.7 permil increase in d18O relative to their source water (Chivas et al., 2002). Large isotopic shifts (up to 8?)  preserved in this record suggest that any intra- or inter-species variability is significantly dampened
size fraction only
similar to ostracod records
Comparison with lake water d18O
Thus, for the past ~5000 years of sedimentation, the n- alkanes in Hakluytvatnet (including short-, mid-, and long-chain homologues) derive predominantly from aquatic moss, and their dD values therefore reflect that of lake water.
Calculated 18O values for aragonite and calcite, precipitated in equilibrium with modern lake water (18Owater = + 2.6a€°) at a mean annual temperature of 25 C, yield values of 0.92a€° and 0.78a€°, respectively (Craig, 1965; Grossman & Ku, 1981). These theoretical values are close to mean values (0.85a€°, 0.47a€°, and 0.39a€°) for recent samples of Cochliogina sp., Pyrgophorus sp., and C. ilosvayi, respectively. This suggests that all three taxa precipitate carbonate near equilibrium with the water in which they live.
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yes
The oxygen fractionation between these modern straw stalactites and the average drip water corresponds to the equilibrium fractionation calculated from the O?Neil et al. (1969) calcite?water calibration at cave temperatures of 16i¿½C (Peqiin) and 18i¿½C (Soreq).
repetition test comparing stable isotopic records from 3 cave sites (Cold Water Cave, Cresco, Iowa; Mystery Cave, Wykoff, Minnesota; Spring Valley Cave, Spring Valley, Monnesota), similar stable isotopic signals of the records indicate that they reflect environmental rather than kinetic effects.
repetition test comparing stable isotopic records from 3 cave sites (Cold Water Cave, Cresco, Iowa; Mystery Cave, Wykoff, Minnesota; Spring Valley Cave, Spring Valley, Monnesota), similar stable isotopic signals of the records indicate that they reflect environmental rather than kinetic effects.
There is little evidence for kinetic fractionation on the basis of C and O isotope correlations. C and O isotope ratios do not correlate strongly for any of the three stalag- mites in this study or even for portions of these stalagmites. The highest R2 value for any of the three stalagmites is 0.27 (table S6). Because the top of D4 was deposited in isotopic equilibrium and because a portion of D4 replicates the Hulu record, D4 is less likely to have been affected by kinetic effects or water/rock interactions than D3.
There is little evidence for kinetic fractionation on the basis of C and O isotope correlations. C and O isotope ratios do not correlate strongly for any of the three stalag- mites in this study or even for portions of these stalagmites. The highest R2 value for any of the three stalagmites is 0.27 (table S6). Because the top of D4 was deposited in isotopic equilibrium and because a portion of D4 replicates the Hulu record, D4 is less likely to have been affected by kinetic effects or water/rock interactions than D3.
There is little evidence for kinetic fractionation on the basis of C and O isotope correlations. C and O isotope ratios do not correlate strongly for any of the three stalag- mites in this study or even for portions of these stalagmites. The highest R2 value for any of the three stalagmites is 0.27 (table S6). Because the top of D4 was deposited in isotopic equilibrium and because a portion of D4 replicates the Hulu record, D4 is less likely to have been affected by kinetic effects or water/rock interactions than D3.
low correlation between d18O and d13C
The d13C profile shows no correlation with d18O in any of the section profiles
statistically significant positive covariation between d18O and d13C (r=0.55,n=103, p<0.01)
repetition test comparing d18O and d13C of two speleothems shows similar trends
repetition test comparing d18O and d13C of two speleothems shows similar trends
repetition test comparing d18O and d13C of two speleothems shows similar trends
repetition test comparing d18O and d13C of two speleothems shows similar trends
Hendy test; lack of correlation between d13C and d18O; replicated stalagmite; prediction from equilibrium constraints matches top values
Hendy test; lack of correlation between d13C and d18O; replicated stalagmite; prediction from equilibrium constraints matches top values
deep cave location
A Hendy Test (S3) shows no substantial isotopic fractionation along the same growth layer and correlations between ?18O and ?13C are statistically insignificant, suggesting that the stalagmite calcite was deposited in isotopic equilibrium (Fig. S3). This agrees with observations from modern carbonate?water stable isotope systematics (S4) from the same cave.
Isotope profiles of all stalagmites are very similar, indicating that So-1 d18O and d13C values are not biased by site-, cave- or sample-specific effects (e.g., kinetic fractionation effects), and furthermore that the So-1 record can be used with confidence for environmental and climatic reconstructions.
Hendy test
equilibrium is evidenced by the lack of correlation among d18O and d13C, several Hendy test in laminations and calculations of explected d18O in modern calcite knowing cave temperatue and d18O from dripwaters (in a previous paper, Sinha et al. GRL (2007)
equilibrium is evidenced by the Hendy test in several laminae and the lack of correlation among d18O and d13C
equilibrium is evidenced by the Hendy test in several laminae and the lack of correlation among d18O and d13C
Given differences in dating errors and resolution, the ?18O records are virtually identical during contemporaneous growth periods, providing a robust replication test for equilibrium calcite deposition.
lack of correlation of d18O and d13c along the growth axis; repetition test showing similar records for contemporaneous samples
lack of correlation of d18O and d13c along the growth axis; repetition test showing similar records for contemporaneous samples
lack of correlation of d18O and d13c along the growth axis; repetition test showing similar records for contemporaneous samples
characteristics and physical conditions of Tzabnah cave, a Hendy test and isotopic equilibrium calculations (Sharp, 2007)
Three Hendy tests were carried out, i.e. at 10mm (AD 70), 20mm (837 BC) and 33mm (1453 BC), based on 7, 7 and 5 samples, respectively. The variations of d18O along individual growth layers, expressed in I”d18O, are 0.31, 0.74 and 0.18%, respectively. The correlation between oxygen and carbon in one of the three layers, at 200 mm, is high, R=0.9 (P<0.01) indicating that kinetic effects may have occurred. The other two test did not show fractionation.
Samples pass the Hendy test
poor correlation of d18O and d13C along the growth axis
There is kinetic isotope fractionation: Strongly positive correlation between d13C and d18O values in the younger segments with Dd13C/Dd18O slopes of 1?1.5. The older parts of the cores are characterized by a significantly lower degree of correlation and typically lower slopes. Linear fits of d13C vs. d18O in cores PFU8 and PFU9 show comparable slopes (1?1.5) but typically lower coefficients (in particular PFU8). Modern calcite precipitates also exhibit a strongly positive correlation of C and O isotope values (R2=0.87). A comparison of the drill core d18O values with calculated modern O isotopic equilibrium values based on monitoring data reveals O isotopic compositions close to isotopic equilibrium only for the calcite d18O minima.
low correlation between d18O and d13C
low correlation between d18O and d13C
equilibrium is evidenced by (1) the lack of correlation among d18O and d13C, (2) the application of fractionation equation with current d18O values in dripwaters and cave temperature and (3) replication with other caves
Hendy tests: stable d18O along growth layers and lack of correlation between d18O and d13C along growth layers
Hendy tests: stable d18O along growth layers and lack of correlation between d18O and d13C along growth layers
Owing to the low cave temperature kinetic isotope effects are minimal (Mangini et al., 2005; Vollweiler et al., 2006).
monitoring of present-day speleothem; Hendy tests
monitoring of present-day speleothem; Hendy tests
Because Bat Cave relative humidity today varies between 70% and 95%, dry conditions are interpreted, in part, to reflect greater kinetic fractionation, resulting in higher ?13C and ?18O values in the stalagmite calcite. The stalagmite was sampled close to the entrance
Poor correlation among d13C and d18O and good overlapping of several stalagmites
Poor correlation among d13C and d18O and good overlapping of several stalagmites
Poor correlation among d13C and d18O and good overlapping of several stalagmites
Poor correlation among d13C and d18O and good overlapping of several stalagmites
Poor correlation among d13C and d18O and good overlapping of several stalagmites
comparion between two individual d18O time series
comparion between two individual d18O time series
The stalagmite ?18O values for the Mexican samples replicate very well over the common time intervals (Fig. S2), suggesting the values have not been significantly affected by kinetic effects, a conclusion that is further supported by an observation of apparent equilibrium isotopic relationships between drip-water samples and modern aragonite precipitating in the cave.
Temp and humidity measured from 2007 till 2013 show constant temp of 8 +/- 0.5 C and humidity close to 100%. Average d18O of 8 drip water samples collected between June, 2007 till July, 2008 is -9.74 +/- 0.48 parts per mille. Glass plate calcite collected over the same period shoed a d18O value of -8.15 parts per mille. So calculated equilibrium temp is 7.6 C which is close to measure cave temp of 7.87 C. Fractionation equation used has not been specified. Supplementary Information.
Samples pass the Hendy Test. Low correlation between d18O and d13C across a layer. Also d18O replicates between stalagmites, but d13C doesnt. Top of stalagmite is similar to predicted value using dripwater d18O and cave temp
equilibrium is evidenced by the lack of correlation among d18O and d13C
low correlation between d18O and d13C
low correlation between d18O and d13C
isotopic equilibrium among rainfall and groundwater data
present day CO2 partial pressure is constant year-round and active steam flow in the cave maintains 100% humidity
present day CO2 partial pressure is constant year-round and active steam flow in the cave maintains 100% humidity
present day CO2 partial pressure is constant year-round and active steam flow in the cave maintains 100% humidity
present day CO2 partial pressure is constant year-round and active steam flow in the cave maintains 100% humidity
present day CO2 partial pressure is constant year-round and active steam flow in the cave maintains 100% humidity
The observation that sponges precipitate aragonite in chemical and isotopic equilibrium indicates that the composition of the precipitating fluid is hardly influenced by the sponge metabolism. Thus pH changes in the ambient seawater may be directly monitored by the d18O record of the sponge aragonite. This hypothesis is supported by the boron isotopic composition of sponge skeletons, which indicates mineralization under seawater pH conditions [Bohm et al., 2000b].
The observation that sponges precipitate aragonite in chemical and  isotopic equilibrium indicates that the composition of the precipitating  fluid is hardly influenced by the sponge metabolism. Thus pH changes in the ambient seawater may be directly monitored by the d18O record of the sponge aragonite. This hypothesis is supported by the boron isotopic composition of sponge skeletons, which indicates mineralization under seawater pH conditions [Bohm et al., 2000b].
mode of skeleton formation of Ceratoporella nicholsoni suggest that these sponges precipitate aragonite close to isotopic equilibrium (bohm, 2000).
mode of skeleton formation of Ceratoporella nicholsoni suggest that these sponges precipitate aragonite close to isotopic equilibrium (bohm, 2000).