Showing papers in "Geochemical Journal in 1971"

Measurements of distribution coefficients and barium between carbonate precipitate —Abnormally high values of distribution measured at early stages of carbonate of strontium and solution coefficients formation

Abstract: The distribution coefficients of Sr and Ba were measured when Mg-poor calcite, Mg-rich calcite or aragonite was precipitated in the calcium bicarbonate solutions containing strontium or barium in trace amounts, MgCl2, NaCl and/or Na-citrate. The abnormally high values of the distribution coefficients were observed very often at the early stages of carbonate precipitation. The conditions, under which such high values are measured, are investigated. And the use of distribution coefficients measured in the laboratory for interpretation of the trace element contents of marine carbonate skeletons is discussed.

Sulfur isotope study of the Kuroko-ores of the Shakanai No. 1 deposits, Akita Prefecture, Japan

Abstract: Sulfur isotope data of the Kuroko-ores from the No. 1 deposits of the Shakanai mine reveal that the δ34S value of sulfide minerals decreases gradually towards the top of the sequence of the stratigraphic and mineralogical zonation of the ores. For example, δ34S values of pyrite show a gradual decrease towards the top of the sequence: +8.2 to +7.2‰ in disseminated ores and veins in the footwall rocks; +6.2 to +5.4‰ in pyrite-ores; +5.5 to +4.6‰ in yellow-ores; +5.6 to +3.0‰ in black-ores; +4.6 to -6.0‰ in hematite-quartz layers. δ34S values of barite in the black-ores are fairly uniform, giving +22∼s+23‰. Sulfur isotope temperatures obtained from coexisting sulfides from different types of ores are fairly consistent, giving temperatures around 250°C (from temperature scales by KAJIWARA and KROUSE, 1970), which is in good agreement with the_ maximum value of a temperature range indicated by fluid inclusion and mineral equilibria studies (ISHIZAKA, 1968; KAJIWARA, 1968). Applications of equilibrium concepts to the observed mineralogy and sulfur isotope data of the ores give the following information: 1) The major source of the ore-forming sulfur was Miocene sea-water sulfate with a δ34S value of around +20‰. 2) Total sulfur content of solutions responsible for the ore-deposition was probably around 0.01 mole/Kg -H2O, which is very close to the value of the present-day sea-water. 3) The observed trend of decreasing δ34S values of sulfide minerals towards the top of the sequence can best be explained by the increase in fo2, pH, and total sulfur content of solutions due to the increasing contribution of sea-water during the ore-deposition. It is thus suggested that the stratigraphic and mineralogical zonation of the ores was also caused by the same mechanism.

Ammonia in the oceanic atmosphere and the cycle of nitrogen compounds through the atmosphere and the hydrosphere

Abstract: The concentration of ammonia in the atmosphere over the ocean was determined for samples collected on board. The concentration of total ammonia in the maritime air was 50ng at/m3(STP) on the average which was much lower than that over the land, and was higher in the air nearer the land. The proportion of aerosol ammonia to total ammonia in the maritime air was 30% (mean) in the North Pacific, whereas it was 80% in the South Pacific. These facts together with the residence time of ammonia in the atmosphere suggest that most of ammonia in the oceanic air is of continental origin. The amount of combined nitrogen transported from the land to the ocean is estimated from its concentration in rain water to be 1.5 × 1012g at N/y. Judging from the budget of the combined nitrogen in the ocean, the large supply of nitrogen from the land is balanced by the denitrification in the ocean. Its mechanism is discussed from the quantitative aspect, and two possibilities still remain owing to the lack of decisive evidences, which are the reduction of nitrate in sea water containing little oxygen and the denitrification in the respiratory process in oxygenated sea water.

An improvement in the carbon-reduction method for the oxygen isotopic analysis of sulphates

Abstract: The carbon-reduction technique for the oxygen isotopic analysis of sulphates has been further developed to improve its reliability for isotopic ratio measurements. Barium sulphate is reduced with carbon at 1, 000°C in a thin platinum boat as an electric resistance heating element to evolve carbon dioxide and carbon monoxide. The carbon monoxide is converted by a high-voltage (3.0kV) discharge between two parallel platinum plates in a liquid-nitrogen cooled vessel. The barium sulphate precipitated from the solution containing sulphate ions by the standard procedure can be reduced with a 98 ± 2% yield of oxygen as carbon dioxide, and analysed with the reproducibility of 0.1-0.25‰ for the oxygen isotopic ratio. No significant memory effect is observed in the analyses of barium sulphates having oxygen isotopic ratios in the range from -1 to +46‰ (SMOW).

Lead-210 and polonium-210 in the surface water of the Pacific

Abstract: >/sup 210/Pb and /sup 210/Po in sea water of the Pacific were determined and applied to make clear the behavior of lead in the surface water of the ocean The concentration of /sup 210/Pb in the surfuce water was much smaller than the expected value, if it were soluble in seawater Its geographical distribution showed a latitudinal variation that presented higher values in both mid-latitudes of the Pacific and lower values in the tropical Pacific and the southern South Pacific These facts suggest that lead is settling with the velocity of (1-5) x 10/sup -4/ cm/sec in the surface layer However, it is very unlikely that the lead exists as pure solid phase of lead oxide The lead probably forms an eutectic solid phase with other host metals such as manganese oxide The ratios of /sup 210/Po to /sup 210/Pb in surface water were larger than those in meteoric precipitation, but most of thera were smaller than unity (auth) Data are presented as a basis of evaluating the increase in activity of waters in the vicinity of Jaslovske Bohunice due to startup of the nuclear power plant The monitoring of radioactivity of waters on the territory of western Slovakia conductedmore » between 1968 and l970 showed that the average annual values were constant and that annual fluctuations were due to an increased fallout and to meteorological conditions (INIS)« less

1971 compilation of data on rock standards JG-1 and JB-1 issued from the Geological Survey of Japan

Abstract: Data of rock analyses, determinations of major and minor constituents, 47 minor elements, strontium isotopic ratios, oxygen isotopic compositions and geological ages reported by analysts for JG-1 granodiorite and JB-1 basalt issued from the Geological Survey of Japan are compiled.

Sulfur isotope study of Kuroko-type and Kieslager-type strata-bound massive sulfide deposits in Japan

Abstract: Sulfur isotope data of sulfide and sulfate minerals from the Kuroko-type deposits of the Miocene age (63 samples of mill concentrates and 48 separate specimens) and from the later Paleozoic so-called Kieslager-type deposits (20 samples of mill concentrates and 11 separate specimens) are reported. The data of sulfides from the Kuroko-type deposits can be divided into two groups, i.e., a lower δ34S group of which deposits in the Ohdate area are representative and a higher δ34S group characterized by deposits in the Kosaka district. A remarkable difference between the Kuroko-type and the Kieslager-type is that the average sulfur isotopic fractionation factor between sulfides and contemporaneous sea-water sulfate is slightly larger in the Kuroko-type deposits than in the Kieslarger-type deposits. Based on the same logic as developed in the previous paper (KAJIWARA, 1971), the difference between the two groups of the Kuroko-type deposits as well as between the Kuroko-type deposits and the Kieslager-type deposits is most likely due to the difference in oxidation state at the time of their deposition, the first mentioned of each pair being higher in oxygen fugacity of ore formation. Similarly, it is also concluded that the “volcanic type” deposits of SANGSTER (1968) are relatively higher in the depositional oxidation state than the “sedimentary type” deposits.

Distribution of rhenium in molybdenites from Japan

Abstract: The rhenium contents of about 200 molybdenites have been determined by the neutron-activation or the catalytic spectrophotometric analyses. The present authors developed these methodes for the determination of the rhenium content of a very wide range, taking only a small amount of each sample. The data obtained show that 1) the rhenium content of molybdenite covers the range from 10-8 to 7 × 10-3 in atomic ratio of Re/Mo, 2) the rhenium contents generally decrease with the following order of occurrence of the molybdenites: volcanic sublimate, porphyry copper deposits, contact-metasomatic deposits, disseminated deposits and quartz veins, 3) as far as plutonic type of molybdenites are concerned, rhenium increases generally with decrease in estimated temperature of molybdenite deposition, 4) the rhenium contents of the molybdenites from Daito area, Shimane Prefecture.as a whole are contrary to the above rule and are higher than those from similar deposits in other areas, 5) low rhenium contents are found in cavity molybdenites, 6) rhenium in an euhedral crystal of molybdenite shows a regular distribution which obeys the Doerner-Hoskins' law, indicating that rhenium forms a solid solution with molybdenum.

Sulfur and oxygen isotopic study of barite concretions from banks in the Japan Sea off the Northeast Honshu, Japan

Abstract: Barite concretions from the Shinguri and other banks of the Japan Sea off the Northeast Honshu have sulfate extremely enriched in heavy sulfur and oxygen isotopes; the δ34S value relative to Canon Diablo troilite ranges from +47.5 to +86.7‰ and the δ18O value relative to SMOW from +24 to +29‰. When δ34S values are plotted against δ18O values, most data closely fit a line having a slope of 4 (Fig.3). Although other possibilities can not be excluded, the isotopic and other geologic features strongly suggest that most plausible environments of their formation were isolated “sea water lakes” which possibly formed on the tops of these banks during the Quaternary glacier ages and where extensive bacterial reduction of sulfate took place. The barite concretions from New Zealand studied by RAFTER and MIZUTANI (1967) and a barite concretion from a bank off Baja, California are isotopically similar to those of the present study.

Oxidation rate of sulfite in water and its bearing on the origin of sulfate in meteoric precipitation

Abstract: The oxidation rate of sulfite was determined in its dilute solution. The reaction is substantially of the first order and the rate is much accelerated by the presence of small amounts of heavy metals such as iron, copper and manganese. The half-life time of sulfite in the natural rain water is more than a few hours. The observed concentration of sulfite in rain water is nil or much smaller than that of sulfate. Thus, the anthropogenic sulfur is removed from the atmosphere after the oxidation to sulfate in air or in cloud droplets. The residence time of aerosol sulfur of anthropogenic origin and the mean-life time of sulfur dioxide for the oxidation are estimated to be 10 days and 30 hrs, respectively, from the concentrations of sulfate and 210Pb in precipitation. It is inferred from the experiments and the observations that excess sulfate in meteoric precipitation is essentially of anthropogenic origin.

Molecular weight distribution of humic acids from lake and marine sediments

Abstract: Molecular weights of humic acids separated from two lake and three marine sediments were measured by gel filtration through Sephadexes. The results indicate that mol. wt. of humic acid distributes from less than 700 to over 200, 000. On the basis of mol. wt. the humic acids are divided into three main groups: (1) components with mol. wt. from 100, 000 to over 200, 000 (43-70%), (2) components with mol. wt. from 5, 000 to 10, 000 (8-25%) and (3) components with mol. wt. less than 700 (10-17%). The humic acids gave rise to lower mol. wt. compounds on acid or alkali hydrolysis, but the ratio of the hydrolyzable portion to the total varied from sample to sample. A possible conversion process of sedimentary humic acids is discussed.

Techniques for the study of fossil tracks in extraterrestrial and terrestrial samples. I: Methods of high contrast and high resolution study

Abstract: Techniques developed for high contrast optical examination and high resolution study of fossil tracks are described. We find that depositing a thin layer of silver (or gold) on the surfaces of trackholes greatly enhances optical contrast allowing accurate measurement of track lengths. This technique has been successfully employed to measure lengths of “complete” tracks using the TINT and TINCLE method. Such measurements are useful in a study of the chemical composition of cosmic radiation and fossil records of transuranic elements in lunar and meteoritic samples. Another application for silver (or gold) coating of track hole surfaces lies in the study of long tracks due to cosmic ray nuclei of Z>30; epoxy resin adheres firmly to the coated surface and the tracks can be sealed against further chemical attack. The plastic replication and Pd shadowing technique was developed and used to examine fossil tracks occurring with high track densities, >107cm-2, in gas rich meteorites and in lunar regolith samples. The method seems to be accurate up to densities of about 3 × 109 cm-2.

K-Ar ages of seamounts along the Japan Trench and the effect of acid leaching on the K-Ar age of a dredged submarine rock

Abstract: The ages of, submarine rocks dredged from seamounts along the Japan Trench were determined by K-Ar method. In order to obtain more reliable age, the effect of acid leaching on an altered submarine rock was examined. Some samples treated by acid solution gave K-Ar ages up to 20% older than the original untreated sample. This result suggests a possibility that, if suitable acid teratment conditions are found, they would result in more reliable ages for submarine rocks. Some submarine rocks dredged from seamounts along the Japan Trench on the oceanic side gave K-Ar ages of about 70-80 m.y, whereas a sample dredged from a seamount on the Japanese Islands side gave a substantially younger age. Considering the present result as well as previous data, the last volcanic activity along the Japan Trench seems to have occurred about 70-80 m.y ago or older.

Phosphorus-32 induced by atmospheric cosmic rays in laboratory chemicals

Abstract: The production rates of 32P in rhombic sulfur were measured at various altitudes from sea level up to the top of Mt. Fuji. The production rate decreases exponentially with increasing atmospheric depth and the dependence indicates that neutron reaction is predominant in the 32P production. From an underground experiment, the contribution of muons to the production of 32P was estimated and the result was compared with relevant data.

Concentration of major chemical elements in marine plankton

Abstract: Plankton samples collected in coastal and offshore areas around Japan were analyzed for sodium, potassium, calcium, magnesium, phosphorus and silicon. Zooplankton samples of single or mixed species were used in the experiment, while phytoplankton samples were only of mixed species. Species composition of mixed samples were determined under a microscope. Generally, phytoplankton are much higher in potassium and silicon contents than zooplankton, while zooplankton are higher in sodium and phosphorus contents than phytoplankton. Magnesium and calcium are relatively abundant in the samples of phytoplankton. A correlation was seen between potassium and sodium contents, calcium and magnesium contents and phosphorus and silicon contents of zooplankton and of phytoplankton. The K/Na ratio of phytoplankton is exceedingly higher than that of zooplankton or seaweeds, while the P/Si ratio of phytoplankton is particularly lower than that of zooplankton or seaweed. On the other hand, the values of Ca/Mg ratio of zooplankton, phytoplankton and seaweeds are very close to each other.

Microscopic determination of iron-organic aggregates in sea and lake waters

Abstract: The size distribution and the aggregation state of particulate organic matter and particulate iron were microscopically observed by the application of histological dyeing method. They were seriously affected by the seasonal water circulation in Lake Haruna. From the results, the formation and the change of particulate iron were suggested. Iron-organic aggregates were observed both in the lake and in the sea, and the significance of their distribution was discussed in relation to the sedimentation of iron and the formation of organic aggregates.

Geochemical study of trace elements in the alkalic rocks of Nemuro Peninsula, Hokkaido, Japan

Abstract: Geochemical data for 13 samples of alkalic rocks from Nemuro Peninsula, Hokkaido, are presented and discussed. Analyses for trace elements, Ni, Co, Cr, Sc, Cu, Zn, Ga, Zr, Y, Pb, Ba, Sr and Li in a differentiated sheet ranging from picritic dolerite to syenite and in an undifferentiated dolerite sheet showing pillow structure, are given. It is shown that the Nemuro alkalic rocks have distinctly higher concentrations of Ba, Zn, Cu, Pb, Y and Li, high ratios of K/Sr and Ca/Sr, and lower concentrations of Sr, Ni, Co, Cr, Sc and Zr than do alkali basaltic rocks from other districts in the world. The behavior of the major and trace elements suggests that the Nemuro alkalic rocks were modified chemically by deuteric alteration during the magmatic stage. The parental potash-rich olivine basalt magma of these alkalic rocks was formed probably by partial melting of phlogopite-peridotite in the upper mantle.

Oxygen isotopic studies of silicate minerals with special reference to hydrothermal mineral deposits

Abstract: Oxygen isotopic compositions of various silicate minerals of sedimentary and igneous origins have been investigated. The determined δ18O values of these hydrothermal silicates vary between -3 and +30‰ most of them correlate well with the crystallization temperature. The δ values of hydrothermal solutions (δW) from which quartz had been deposited have been calculated. The values thus calculated for samples which crystallized at temperatures above 300°C show a samll variation about a mean value of +8‰ and decrease systematically with temperature below 300°C. An ore fluid that existed above 300°C is interpreted as having equilibrated with a large reservoir of silicate rocks at high temperatures on the basis of 18O content. The variations of δW with temperature for samples which crystallized below 300°C are attributed to the mixing of the ore fluid with 18O-poor meteoric water. This view supports the cooling mechanism of hydrothermal ore fluids, which was proposed by BARTON and TOULMIN (1961). Hydrothermal solutions of ore deposits of shallow, so-called “subvolcanic” origin, however contain large proportions of meteoric water. The isotopic composition of the initial hydrothermal solution can be measured directly only in fluid inclusions in minerals deposited above 300°C and with no oxygen atoms. When ore deposits are classified, the separation of the group of deposits as “volcanic” or “subvolcanic” is helpful.

Thin layer chromatographic method for determining plant pigments in marine particulate matter, and ecological significance of the results

Abstract: Thirty to 100 liters of sea water sample containing MgCO3 powder was filtered through a glass fiber filter in order to collect particulate matter. Soon after the filtration, this glass fiber filter was kept in a deep freezer ( -20°C) for later use. The following pigment analysis was carried out within a week. Plant pigments in the collected particulate matter were extracted with 90% acetone in a dark refrigerator. Pigments in the acetone extract were separated by thin layer chromatography using a mixture of cellulose powder and soluble starch as an adsorbent. The developing solvent was 1.2% n -propanol in petroleum ether. According to this procedure, 9 kinds of pigments were fractionated. Each of the fractionated pigments was eluted with 90% acetone and determined by measuring fluorescence of the acetone extracts after acidification with a small amount of hydrochloric acid . The analyses of sea water samples from the central Pacific showed the following facts: (1) Vertical distribution of chlorophyll a had a peak at a depth of 100m or 150m and its amount remarkably decreased with depth in parallel with the total pigments. (2) The percentage of chlorophyll a in the total pigments was more than 60% for the sea water samples examined, even at the depth of 1,000m. (3) The absence of phaeophytin a was made clear for the samples examined,

Pressure-temperature conditions for the formation of peridotite inclusions. —An application of a regular solution model to partitioning of Mg, Fe and Co between coexisting olivine and orthopyroxene—

Abstract: The partitioning of Mg, Fe and Co between coexisting olivine and orthopyroxene found in peridotite inclusions is examined from the thermodynamic point of view, using a binary and a ternary regular solution models. The following two exchange reactions are considered: MgSi0.5O2+FeSiO3 = FeSi0.5O2 +MgSiO3 (1) and MgSi0.5O2+CoSiO3=CoSi0.5O2+MgSiO3. (2) The apparent partition coefficients are respectively: RT·lnK'Fe.Mg=-ΔG1-(2XMg01-1)(W01P+α01)+(2XopxMg-1)(WopxP+αopx) (3) and RT·lnK'Co.Mg=-ΔG2+(Δα+ΔWP)XFe (4) Using (3) and (4), we can estimate the P-T conditions at equilibrium of peridotite inclusions, if we know the numerical values of the apparent partition coefficients. Examination of the equilibrium relations in a peridotite inclusion from a South African kimberlite and in an lchiomegata lherzolite leads to the conclusion that the garnet peridotite is formed at higher pressure and lower temperature than the lherzolite.

Oxygen isotope study of the Koyama intrusive complex, Yamaguchi-Prefecture, Southwest Japan

Abstract: The Koyama intrusive complex consists of varying rock-types from olivine pyroxenite to aplite as a consequence of differentiation of gabbroic magma. The whole-rock δ18O values of the main differentiates are +6.2 to +6.6‰ (in SMOW) for olivine rich members and are invariably around +7.8‰, from quartz gabbro to aplite. It is suggested that the Koyama magma differentiated without any significant isotopic fractionation. The isotopic difference between the two groups is largely due to the concentration into the former of olivine and pyroxenes which are isotopically lighter than plagioclase. The results support the view that the major rock-types are formed by the gravity sorting and accumulation of olivine, pyroxenes and plagioclase. Among the minor members of the complex, “granular” gabbro and a quartz diorite dyke are depleted in 18O by 2 to 3‰ compared to the major rock-types, whereas the veins of augite and of plagioclase-hornblende exhibit higher 18O content. It is suggested that a simple contamination of the residual magma by wall rock basalt can not produce such isotopic anomalies.

Uranium, thorium and potassium contents of St. Paul's rocks

Abstract: Neutron activation analysis of uranium, thorium and potassium has been. made on St. Paul's rocks of possible oceanic mantle origin. Results of analysis showed that average values of WISEMAN's “challengerite” are (15.8 ± 0.5) × 10-8 gU/g, (34.5 ± 1.0) × 10-8 gTh/g and (3100 ± 60) × 10-6 gK/g, giving a rate of heat production of ca. 300 × 10-16 cal/cm3·sec. This value agrees with the rate expected for the pyrolitic oceanic upper mantle. Other types of St. Paul's rocks, such as “owenites”, “paulites” and “questites” were shown to contain these elements comparable in amount with peridotite nodules. The Th/U ratio of these rocks, however, is unusually low.