MTT44-P01

Room:Convention Hall

Time:May 26 18:15-19:30

Simultaneous determinations of 58 elements in volcanic glass shards using the femtosecond laser ablation ICP-MS
MARUYAMA, Seiji1∗ ; HATTORI, Kentaro2 ; HIRATA, Takafumi2 ; SUZUKI, Takehiko3 ; DANHARA, Tohru1
1

Kyoto Fission-Track Co., Ltd., 2 Department of Geology and Mineralogy, Faculty of Science, Kyoto University, 3 Department ofGeography, Tokyo Metropolitan University
Volcanic glass shards in the Quaternary widespread tephras have been chemically classified and identified on the basis of thecontents of the major components (e.g. Al2 O3 , CaO, and MgO) determined using the electron beam microanalysis techniques.
The abundances of the trace elements have been also measured using various analytical techniques including INAA, ICP-AES,and laser ablation ICP-mass spectrometry (LA-ICP-MS) techniques. However, the measurements of the trace elements havebeen generally restricted to the rare earth elements and some elements such as strontium, thorium and uranium. In this study, we
carried out the quantitative analyses of the total of 58 elements from lithium to uranium simultaneously using the femtosecond
LA-ICP-MS technique. Four volcanic glass samples on the International focus group on Tephrochronology And Volcanism (INTAV) sample mount described by Kuehn et al. (2011) were analyzed for comparison between the analytical values of the major
components using the LA-ICP-MS technique and those obtained by the electron beam microanalysis techniques. The analyticalvalues of the major oxide components of the INTAV volcanic glass samples deviate less than 10% from the preferred values
shown in Kuehn et al. (2011). The analytical results suggests that the LA-ICP-MS technique can be reasonably available forquantitative analyses of the major elements in volcanic glass shards in addition to the trace elements, as an alternative of electron
beam microanalysis techniques. We analyzed 22 tephra samples from Japan and surrounding region (e.g. Aira Tn tehphra andAso-4 tephra) and 4 tuff samples of North America (e.g. Lava Creek Tuff and Bishop Tuff), and confirmed that the volcanic glass
shards can be clearly distinguished from each other by the patterns of the wide-ranged element abundances. The abundances
and the patterns of the wide-ranged elements of the volcanic glass shards are definitely helpful to more precise identification andcorrelation of tephra samples.
Keywords: volcanic glass, tephra, LA-ICP-MS, element abundance, element pattern, femtosecond laser

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MTT44-P02

Room:Convention Hall

Time:May 26 18:15-19:30

Attempt to measure magnetization of single pollen in microgravity condition
UYEDA, Chiaki1∗ ; OGINO, Satoshi1 ; HSAYOSHI, Keiji1
1

Graduate School of Science

Precise analyses performed on microfossil pollen included in the soil have provided quantitative information to reconstruct
the paleoclimate. In order to improve the precision of the chronical data, it is necessary to reduce the lower limit of detectable
number of pollen included in the sample per unit volume. In analyzing an aggregate sample composed of heterogeneous grains,
it is often difficult to conclude by visual observations whether or not the minor grains included in the sample are completely
discovered and identified without omission. In such cases, it is desirable to separate the aggregate in to single grains and identify
their material prior to various scientific researches. It was proposed that identification of solid grain is possible by comparing thegrain’s magnetization obtained by field-induced translation, with the compiled data of magnetization [1]. The proposed principleof identification has significance in investigating rare samples, such as primitive meteorites, because the method can analyze thesmall grains in a simple manner without consuming them.
In order to quantitatively evaluate the practicability of separating the microfossil pollen from the soil mineral grains, it isnecessary to the precise value of magnetic susceptibility of pollens. Therefore, M-H curves were measured for two kinds ofpollen, namely plum and hinokia cypress using a vibrating sample magnetometer VSM. The measurements were performed bysweeping static field between -0.5 and 0.5 T at room temperature. In addition to the diamagnetic relationship expected for theorganic chemical composition of pollen, features that indicate saturated moments Ms were observed in the M-H curves of plumpollen, while no evidence of Ms was observed for hinokia cypress. The Ms values showed linear correlations with sample mass
m for the two samples. The above-mentioned results magnetization results chemical analysis.
[1] K. Hisayoshi & C. Uyeda, J. Jpn. Soc. Microgravity Appl., (2012).

Keywords: pollen, fossil, identification, magnetic field gradient, microgravity

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MTT44-P03

Room:Convention Hall

Time:May 26 18:15-19:30

Development of new ion collector for U-Pb Age cytometry
HIRATA, Takafumi1∗ ; HATTORI, Kentaro1 ; SAKATA, Shuhei1 ; ORIHASHI, Yuji2
1

Kyoto University, 2 Earth Research Institute, The University of TokyoAge distribution (age cytometry) is one of the most principal and versatile information to decode the geological events underlying the Earth evolution. To take full advantage of the age cytometry, both the high analytical throughput and the better
precision in the age determination is severely desired. Combination of laser ablation sampling technique and the high-sensitivity
ICP-mass spectrometer (LA-ICPMS) enables us to measure precise U-Pb ages directly from the small area in the solid samples.
Recently, both the precision and reliability of the U-Pb age data was dramatically improved by both the newly developed ion
counting technique using the attenuator device and the correction technique for the initial disequilibrium for the U-Th-Pb decay
series (Sakata et al., 2014). Moreover, magnetic sector-based mass spectrometry equipped with the multiple-ion counting system
results in much higher analytical precision in the Pb/U and Pb/Th isotope ratio measurements. With the multiple-ion counting
system, the analysis time for the U-Pb age determination could be dramatically shortened down to 1 - 5 sec, which was almost
1/4 - 1/10 levels over the conventional U-Pb age determinations using the single collector ICPMS instruments. This suggests thatboth the higher analytical throughput and the better precision in the Pb/U ratio measurements could be achieved. The problem
associated with the multi-ion counting technique would be a time-dependent changes in the gain and the background (dark noise)of the multipliers. This is one of the large sources of analytical error in the U-Th-Pb age determinations. To overcome this,multiple-ion counting system using Daly ion collectors was employed in our MC-ICPMS system.
Several unique features could be achieved by the Daly ion counter, such as (a) wider dynamic range of the ion counting up to<10 Mcps, (b) smaller time-changes in gain and background level of the collector, and (c) better peak parallelism (peak flatness)over the conventional multipliers. Only the problem associated with the Daly counter is that the width of the Daly collector would
be significantly larger than the mass dispersion for the heavier elements. In this study, two pairs of ion deflectors were used toobtain wider mass dispersion for the ion beams. With the multiple ion counting using the Daly ion counters, better precision andsmaller contribution of the time-dependent changes in the gain and background counts could be achieved.
In this presentation, new ion collector system was applied to the MC-ICPMS system, and the preliminary results on the Pb/U
and Pb/Th isotope ratio measurements and age determinations on zircon samples will be described.

Keywords: Age Cytometry, Multiple Ion Counting, Laser Ablation, U-Pb Dating, Zircon Chronology

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