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The oxygen isotope (δ 18 O) 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 δ 18 O offset (Δ 18 O SIMS-GSMS ) of −0.9 ± 0.1‰ (±2 SE). The volume of material analyzed in 10-μm SIMS spots is ~10 5 times smaller than that analyzed by GSMS; hence, the extent to which these Δ 18 O SIMS-GSMS values represent real differences in analyte vs. instrumental factors remains unclear. Possible contributing factors to the SIMS-GSMS δ 18 O 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 δ 18 O variability delineated by shell fragment GSMS values. This strong positive covariance proved useful for bringing the two datasets into agreement (i.e. Δ 18 O SIMS-GSMS  = 0), and confirms that SIMS-based foraminifer δ 18 O values record changes in calcification temperature and/or δ 18 O of seawater. Whether shells of foraminifer taxa with differing microcrystalline structures, chemical composition, and/or preservation histories register a similar Δ 18 O SIMS-GSMS value is a subject of ongoing testing. [ABSTRACT FROM AUTHOR]

Two baddeleyite megacrysts were evaluated as potential reference materials (RMs) for SIMS oxygen isotope analysis, and utilized to understand and calibrate instrumental mass fractionation (IMF). A baddeleyite crystal (S0045) from the Phalaborwa carbonatite, South Africa has a mean δ 18 O VSMOW  = +4.6 ± 0.3‰ (range 0.75‰) measured using laser fluorination gas source mass spectrometry (LF-GMS) and one (S0069) from the Mogok metamorphic belt, Myanmar has δ 18 O VSMOW  = +22.2 ± 0.4‰ (range 0.89‰). SIMS standardization utilizing these inherently heterogeneous RMs is possible by analyzing a number of crystal fragments and utilizing one of them lying at the median of the range. Metamictization, lattice orientation, and chemical composition do not appear to be significant (<0.5‰) variables in matrix matching of RMs and unknowns. Propagation of errors while utilizing the imperfect RMs results in 10 μm diameter spot uncertainties of about ±0.3‰ (2σ). SIMS oxygen isotope analysis of co-crystalline zircon and baddeleyite from the 2.2 Ga Duck Lake sill (DLS) in the Northwest Territories, Canada, yield predominant δ 18 O VSMOW modes of +6.0‰ and +3.2‰, respectively. This difference is consistent with preserving high-temperature isotopic equilibrium between zircon and baddeleyite. DLS baddeleyite δ 18 O data as a whole are negatively skewed (to 0.0‰), and interpreted to reflect low temperature, open-system behaviour. Zircon δ 18 O are less affected, but also show hints of the same influences of secondary alteration and oxygen isotope exchange. [ABSTRACT FROM AUTHOR]

The high resolution infrared spectra of the 32 S 16 O 18 O molecule were recorded with a Bruker IFS 120 HR Fourier transform interferometer for the first time in the region of 1800–2800 cm −1 where the bands 2 ν 1 , ν 1 + ν 3 , and 2 ν 3 are located. About 3970, 2960 and 3450 transitions were assigned in the experimental spectra with the maximum values of quantum numbers J max . / K a max . equal to 59/20, 68/25, and 43/18 to the bands 2 ν 1 , ν 1 + ν 3 , and 2 ν 3 , respectively. The subsequent weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes into account the resonance interactions between the studied vibrational states. As the result, a set of 39 fitted parameters was obtained which reproduces the initial 3213 ro-vibrational energy values obtained from the assigned transitions with the d rms = 2.4 × 10 − 4 cm − 1 . [ABSTRACT FROM AUTHOR]

The central Fennoscandia is characterized by the Archean-Proterozoic (AP) boundary and the Central Finland Granitoid Complex (CFGC), a roundish area of approximately 40,000 km 2 surrounded by supracrustal belts. Deep seismic reflection profile FIRE 3A runs across these units, and we have re-interpreted the profile and crustal evolution along the profile using 1.92–1.85 Ga plutonic rocks as lithospheric probes. The surface part of the profile has been divided into five subareas: Archean continent (AC) in the east, AP, CFGC, boundary zone (BZ) and the Bothnian Belt (BB) in the west. There are 12 key samples from which zircons were studied for inclusions and analyzed (core-rim) by ion probe for U–Pb dating and oxygen isotopes, followed by analyzes for Lu–Hf by LA–MC–ICP–MS. The AC plutonic rocks (1.87–1.85 Ga) form a bimodal suite, where the proposed mantle source for the mafic rocks is 2.1–2.0 Ga metasomatized lower part of the Archean subcontinental lithospheric mantle (SCLM) and the source for the felsic melts is related plume-derived underplated mafic material in the lower crust. Variable degrees of contamination of the Archean lower crust have produced “subduction-like” Nb–Ta anomalies in spidergrams and negative ε Nd (T) values in the mafic-intermediate rocks. The felsic AC granitoids originate from a low degree melting of eclogitic or garnet-bearing amphibolites with titanite ± rutile partly prevailing in the residue (Nb–Ta fractionation) followed by variable degree of assimilation/melting of the Archean lower crust. The AP plutonic rocks (ca. 1.88 Ga) can be divided into I-type and A-type granitoids (AP/A), where the latter follow the sediment assimilation trend in ASI diagram, have high δ 18 O values (up to 8‰) in zircons and exhibit negative Ba anomalies (Rb–Ba–Th in spidergram), as found in sedimentary rocks. A mixing/assimilation of enriched mantle-derived melts with melts from already migmatized sedimentary rocks ± amphibolites is proposed. The CFGC is characterized by both I-type and A-type (CFGC/A) intermediate and felsic granitoids. The I-type granitoids are divided into two groups at ≥ 1885 Ma and ≤ 1882 Ma, where the latter overlap in age with the CFGC/A granitoids. Both I-type CFGC and CFGC/A granitoids are interpreted to have formed from mixing of Paleoproterozoic SCLM-derived melts with crustal melts from hydrous and dry intermediate-felsic igneous sources, respectively. The geochemistry, dominantly δ 18 O values below 6.5‰ in zircons and T DM (2.11–2.42 Ga) of the CFGC granitoids favor the occurrence of older crust (ca. 2.1–2.0 Ga) in their genesis. The BZ granitoids are similar in age but more juvenile with T DM ages between 1.94 Ga and 2.16 Ga. The 1.92 Ga granodiorite in the BB is correlated with juvenile gneissic tonalites and granodiorites found from the AP boundary. We suggest that the present high-velocity lower crust under the CFGC is composed of melt-extracted granulites (crustal source age ≥ 2.0 Ga) and mafic cumulates which both formed during 1.90–1.88 Ga arc magmatism. The ≤ 1.88 Ga stage represents the end of compression/transpression and is followed by 1.87–1.86 Ga buckling, forming the Bothnian Oroclines. [ABSTRACT FROM AUTHOR]

Background: Theoretical calculations have shown that the energy and angular correlations in the three-body decay of the two-neutron unbound 260 can provide information on the ground-state wave function, which has been predicted to have a dineutron configuration and 2n halo structure. Purpose: To use the experimentally measured three-body correlations to gain insight into the properties of 260, including the decay mechanism and ground-state resonance energy. Method: 26O was produced in a one-proton knockout reaction from 27F and the 24O + n + n decay products were measured using the MoNA-Sweeper setup. The three-body correlations from the 26O ground-state resonance decay were extracted. The experimental results were compared to Monte Carlo simulations in which the resonance energy and decay mechanism were varied. Results: The measured three-body correlations were well reproduced by the Monte Carlo simulations but were not sensitive to the decay mechanism due to the experimental resolutions. However, the three-body correlations were found to be sensitive to the resonance energy of 26O. A 1σ upper limit of 53 keV was extracted for the ground-state resonance energy of 26O. Conclusions: Future attempts to measure the three-body correlations from the ground-state decay of 26O will be very challenging due to the need for a precise measurement of the 24O momentum at the reaction point in the target. [ABSTRACT FROM AUTHOR]

Oxygen isotopic composition was determined on representative samples of the Cape Ashizuri plutonic rocks, in order to estimate the genetic background of the biotite granite and alkaline granitoids. The biotite granite (70.1-76.1% SiO2) ranged from 8.61 to 9.30‰ δ18O and averaged as 8.9‰ δ18O (n = 3), which is much smaller than the same Miocene granitoids of the Okueyama (avg. 10.1‰) and Takakumayama (11.6‰) granitic bodies, which are associated with tin mineralization. Among the alkaline granitoids, quartz syenites also have values as low as 7.14-8.70‰, with an average of 8.0‰ (n = 3), and monzonite and gabbro vary from 6.14 to 7.86‰, with an average of 7.0‰ (n = 3). These alkaline granitoids may be lower crustal in origin. The gabbroids containing 12.5% MgO at the maximum with low Sr initial ratio, are considered to be derived from the upper mantle through the fore-arc tectonic break-up on the subducting slab. [ABSTRACT FROM AUTHOR]