Abstracts of Annual Meeting of the Geochemical Society of Japan

Jurassic and Cretaceous granitoid bodies are widely distributed in the Sanandaj-Sirjan Zone (SaSZ) of the Zagros Orogen. The Shalair Valley granitoid plutons in NE Iraq are located within Iraqi Zagros Suture Zone which is considered as an integral part of SaSZ in Iran, and several types of granitoid are distributed there. In this study, we reported radiometric ages and chemical and Sr-Nd isotopic features of the Shalair Valley granitoids.

View full abstract

So far, volatiles in the terrestrial atmosphere and oceans have been considered to have been originated due to degassing from the Earth's interior during early period of the Earth's history. In recent years, it has been proposed that such volatiles including water might have been transferred to the Earth by late veneer which had been considered to explain PGEs pattern in the mantle and some other signatures. So far, noble gas isotope signatures have been explained based on the degassing from the Earth's interior and the effect of late veneer has not been well examined. In this talk, I will discuss the effect of late veneer(s) to the noble gas signatures.

View full abstract

In this study the oceanic εNd values recorded by manganese crusts are interpreted in terms of newly-identified diatomaceous ocean weathering as well as normal weathering carried out on lands (terrestrial weathering). The two types of weathering are assumed to be functions of oceanic silicic acid concentration and atmospheric CO2 concentration. The two environmental variables have been discovered to strongly be coupled most of time, but exhibit decoupling around 3 Ma ago. The implication will be discussed with relevance to the emergence of glacial periods.

View full abstract

Show abstractHide abstract

The concentrations of acid volatile sulfides (AVS) in three different size fractions (< 10 nm, 10-200 nm, > 200 nm) at lake Teganuma was measured using nano-size filtration method and a series of acid addition, Helium purge, and GC-FPD analysis. Fresh water sampling was obtained from four sites and filtration using 30 nm or 0.2 µm pore size filters for size fractionation was immediately made on site. The concentrations of AVS for unfiltered fractions were in the range of 0.6-1.4 nmol/kg in this study, and the highest values of AVS were observed in the lotus field station. For the relative concentration ratios of size fractionated AVS for three size fractions of < 30 nm, 30-200 nm and > 200 nm, it is almost same ratios for the all stations, except for the lotus station, and ~80% of metal sulfides fractions were existed as size fractions of < 10 nm, and there were only 10% or so for both 30-200 nm and > 200 nm size fractions with respect to the unfiltered fraction. On the other hand, in the lotus station, the contribution of < 30 nm fraction was contributed only ~5% and ~80% of metal sulfides fractions were significantly existed as size fractions of 30-200 nm, although the total AVS concentration of the lotus station is almost the same level as the other stations.

View full abstract

Download PDF (128K)

Register with J-STAGE for free!