D/H ratios of the coexisting phlogopite and richterite from mica nodules and a peridotite in South African kimberlites

The water content and D/H ratio of pairs of phlogopite and richterite in kimberlite samples were measured. The water contents of both minerals were lower than the formula content. On the basis of D/H ratios of the pair, phlogopite and richterite can not be regarded as a simple equilibrium product with respect to hydrogen isotope exchange. It seems impossible to estimate D/H ratio of the mantle water through D/H ratios of the hydrous silicate pairs.     

Decay of a post-depositional remanent magnetization in wet sediments due to the effect of drying

Summary. The decay of the post-depositional remanent magnetization (post-DRM) during desiccation in magnetic field free space is measured as a function of the loss of water. The decay is ascribed to the drying effect and the time decay of viscous remanent magnetization (VRM). The VRM forms only 10 per cent of the total of loss of remanent magnetization. The decay due to the drying effects depends both on the loss of water and on either the evaporation rate or the period of storage. The percentage of loss of magnetization is independent of its intensity.
A critical drying stage appears (about 60 per cent in water content on a dry basis) which is characterized as a vanishing point of mobile particles or particle units. The mobile particles or units play an important role both in acquisition and demagnetization through physical rotational motion within wet sediments before the critical drying stage. More than 80 per cent of the total loss of the post-DRM is destroyed before the desiccation proceeds to the critical drying stage. The decay of post-DRh4 is concluded to be mainly due to the physically random rotation of the magnetic particles trapped in shallow energy wells which are overcome by the torques caused by the application of the alternating magnetic field less than 200 Oe.     

Temporal variability in physicochemical properties,phytoplankton standing crop and primary production for 7 years (2002–2008) in the neritic area of Sagami Bay,Japan

Seasonal and interannual variations in physicochemical properties (i.e., temperature, salinity, dissolved oxygen and dissolved inorganic nutrients), chlorophyll a (Chl-a), particulate carbon and nitrogen (PC and PN, respectively), and primary production were investigated in the neritic area of Sagami Bay, Kanagawa, Japan, from January 2002 to December 2008. These abiotic/biotic variables, except for NH₄ ⁺–N, repeated similar seasonal variations for all 7 years. On the basis of the analysis of data obtained on 167 sampling dates, depth-integrated primary production in this water can be easily estimated from Chl-a at the surface using the regression equations obtained in the present study. Intermittently high values of dissolved inorganic nutrients, Chl-a, PC, PN and primary productivity at the surface during the summer stratified period were induced by high freshwater discharge from the rivers after rainfalls and by the expansion of nutrient-rich Tokyo Bay Water. Temperature, salinity and dissolved inorganic nutrients showed drastic variations within a scale of a few days and/or weeks, and these variations were related to sea levels that represent the intrusion of the Kuroshio Water, Intermediate Oyashio Water or deep water from the continental slope. However, there was no consistent trend in the variations in Chl-a, PC, PN and primary production due to the complex effects of these waters.     

Spatial and Temporal Changes of Floating Population in China Between 1990 and 2000

By studying the county-level census data of 1990 and 2000, we analyzed the spatial and temporal changes in the floating population in China between 1990 and 2000. The results of the analysis revealed the following characteris- tics. First, the spatial distribution of the migrants (referred to as 'floaters' in this paper) became increasingly concentrated in the cities during the 1990s. Second, the number of floaters increased rapidly during this period, and the area in which the floaters settled expanded quickly into four population explosion belts: the coast, the Changjiang River Delta, the Beijing-Guangzhou Railway and national border belts. Third, the number of inter-province floaters increased rapidly and exceeded that of intra-province floaters in the 1990s. In addition, to obtain a quantitative relationship between the number of floaters and 10 socio-economic variables by using statistical methods and also to find the chiefly important pulling factors of the migration destination, the authors selected approximately 100 cities with the largest population of floaters. Consequently, we found that four factors-GDP, passenger trips per 10,000 persons, per capita GDP and foreign direct investment-could provide an explanation for 83.7% of the number of floaters in 2000. The GDP showed the highest correlation with the number of floaters, suggesting that a highly developed economy is the most important factor that attracts floaters. Furthermore, a fairly close relationship between the number of floaters and the GDP was also found in 2000 for all the counties.     

Hydrogen isotope composition of deep-seated water

D/H ratios of phlogopites and amphiboles from rocks of possible mantle origin and also those of water from (glass?) inclusions in olivines of the olivine nodule and peridotites have been determined. The mantle water seems to have aδD value of —85±10‰ on the basis of results of inclusions in the nodule-olivine.     

MINERALOGY,PETROGRAPHY AND CHEMISTRY OF THE CHONDRITE,KAMIOMI, SASHIMA-GUN,IBARAKI-KEN,JAPAN

The Kamiomi, Sashima-gun (Iwai-shi), Ibaraki-ken, Japan, chondrite (observed to fall in spring, during the period 1913–6), consists of olivine, orthopyroxene, nickel-iron and troilite with minor amount of plagioclase, clinopyroxene, apatite and chromite. The average molar composition of olivine (Fa₁₉) and orthopyroxene (Fs₁₇) indicates that Kamiomi is a typical olivine bronzite chondrite. From the well-recrystallized texture, the presence of poorly-definable chondrules, homogeneous composition of olivine and absence of glass, this chondrite could be classified in petrologic type 5. The bulk chemical composition, especially, total Fe (27.33%) and metallic Fe (17.00%) as well as Fe_total/SiO₂(0.72), Fe_metal/Fe_total (0–633) and SiO₂/MgO (1.59) support the above conclusion. Coexistence of heavily-shocked olivine grains in the matrix composed of olivines and pyroxenes which suffered from light to moderate shock effect suggest that impacting phenomena, small-scaled but locally strong, occurred on the Kamiomi parent body.     

A preliminary study of D/H ratios of chlorites

Chemistry dependence of D of chlorites is inferred from data for natural chlorites. D of water equilibrated with those chlorites is estimated to be –2–8.