Sulfur isotope study of Quaternary volcanic rocks from the Japanese Islands Arc

The sulfide and sulfate contents and their δ³⁴S values were determined in Quaternary volcanic rocks from the Japanese Islands Arc. The total sulfur contents are much lower (less than 40 ppm) and the δ³⁴S values are higher (+4.4 ± 2.1) than those of ocean-floor basalts (800 ± 100 ppm and +0.8 ± 0.5, respectively; Moore and Fabbi, 1971; Sakaiet al., 1982). Lateral variations of both sulfur content and δ³⁴S values were observed in the four volcanic belts in Japan. In the Northeast Japan belt, the sulfur content (30 ± 10 ppm) of the rocks in the inner zone (the Japan Sea side) is 3 to 5 times that in the outer zone (the Pacific side), although the δ³⁴S values of the two zones are almost the same (+4.3 ± 1.0). The δ³⁴S values for the two belts in West Japan are on the average 2%. higher than those of East Japan.This study suggests that the primary magmas that formed the island arc volcanic rocks are initially depleted in sulfur (<120 ppm) and enriched in ³⁴S ($\text{δ}{}^{34}\text{S: +5 ～ +7}$) compared to ocean-floor tholeiitic basalts which formed at mantle under oceanic region. This indicates that the upper-mantle is heterogeneous in sulfur content and isotope composition.     

A thermochemical study of glasses and crystals along the joins silica-calcium aluminate and silica-sodium aluminate

Enthalpies of solution in molten 2PbO · B₂O₃ at 985 K are reported for series of glasses xCa_0.5AlO₂-(1?x)SiO₂ (O ≤ x ≤ 0.99) and xNaAlO₂-(1?x)SiO₂ (0 ≤ x ≤ 0.56). The data are compared to values for the corresponding crystalline aluminosilicates and to preliminary data for systems containing KAlO₂ and Mg_0.5AlO₂. The enthalpies of mixing of glasses become more exothermic with increasing basicity of the mono- or divalent oxide. The tendency toward immiscibility on the silica-rich side, indicated by the shape of the heat of mixing curve between x = 0 and x = 0.4, is pronounced in the calcium aluminate system, but not in the sodium aluminate system. The shape of the heat of mixing curve, which is roughly symmetrical about x = 0.5, can be rationalized in terms of glass structure by considering essentially random substitution of Si and Al on a continuous three dimensional tetrahedral framework, with stabilization arising from electrostatic interactions between aluminum and the nonframework cation balancing the destabilizing effects arising from perturbation of the aluminosilicate framework by the nonframework cation. These trends are consistent with the variation of physical properties of aluminosilicate melts.     

Genesis of Recent silicic magmatism in the Medicine Lake Highland,California: evidence from cognate inclusions found at Little Glass Mountain

We use granular inclusions and phenocrysts in the Little Glass Mountain rhyolite flows to estimate temperature, pressure and the fugacities of O₂, H₂ and H₂O. The compositions of magnetite-ilmenite are used to estimate temperature and oxygen fugacity. Fugacities of H₂ and H₂O are estimated from the compositions of associated biotite-sanidine-magnetite. P_Total depends on the compositions of magnetite -ferrosilite-silica. Lastly, hydrothermal experiments were conducted at the estimated T, P and f_O2 to establish the beginning of melting of the most evolved of the inclusions in CO₂-H₂O fluids.The data suggest that the most evolved inclusions formed at ～ 830°C, a total pressure of 5200 bars, f_O2 of 10^?13 and P_H2O ～ 1000 bars. Of these variables total pressure is most difficult to estimate accurately. The values of T, P etc., previously stated produce a maximum estimate of the depth of equilibration between host magma and the inclusions whereas, assuming P_H2O = P_Total yields a minimum estimate. The physical conditions together with texture suggest a plutonic origin at a minimum depth of 3.4 km but no deeper than 15–18 km beneath the Medicine Lake Highland.The composition and mineralogy suggest that the rhyolite was derived from the dacite by crystal fractionation. The relation between dacite and associated basaltic or andesitic rocks is uncertain. The ${}^{87}\text{Sr}{}^{86}\text{Sr}$ ratios (essentially 0.7040 for both inclusions and lavas) do not require involvement of crustal rocks. A source in the uppermost mantle or lower lithosphere is considered most probable for the parental liquid which gave rise to the dacite.     

1H NMR spectra of humic and fulvic acids and their peracetic oxidation products

¹H NMR spectra of humic (HA) and fulvic (FA) acids and their oxidative degradation products are reported. The HA shows the presence of -(CH₂)_n - CH₃ (n > 6) chemical fragments belonging to n-alkanes and/or n-fatty acids physically adsorbed onto the macromolecule structure. These fragments are absent in the FA fraction. Both humic fractions reveal the presence of similar amounts of aromatic protons which partly undergo exchange phenomena. The importance of this experimental observation is discussed. Oxidative degradation seems to cause partial cleavage of aromatic rings, more pronounced in the FA than in the HA. The degraded FA shows a higher total acidity and a higher phenolic OH content than the degraded HA. Both degraded fractions display some sharp singlet signals at 1.9 and 3.9 ppm arising from protons belonging to repetitive chemical fragments probably formed during the oxidation reaction. Tentative assignments of these signals are given. A general analysis of the HA and FA degraded spectra seems to indicate that the chemical fragments which undergo peracetic oxidation are substantially similar. The extent of oxidation of the two humic fractions is different. The HA degradation products reveal the presence of oligomeric structures, whereas the degraded FA appears less resistant to the oxidizing agent.     

δ13C food web analysis of a Texas sand dune community

Stable carbon isotope ratios (δ¹³C) were determined for 31 plant and 16 animal species from a sand dune community on the south Texas coast. Plants and insects had similar δ¹³C values, forming two distinct groups, while herbivorous rodents formed a third intermediate group. This suggests that insects at the study site are specialists which feed on C₃ or C₄ plants, while the rodents are generalists, feeding on plants of both groups.     

Stable carbon isotope ratios in Astrangia danae: evidence for algal modification of carbon pools used in calcification

Stable carbon isotope ratios have been measured in skeletons of the temperature shallow water scleractinian coral, Astrangia danae. δ¹³C values ranging from ?5.42 to ?7.30%. revealed the expected depletion of ¹³C in skeletal carbonate relative to sea water bicarbonate. Differences among the ratios could not be attributed to collection site and were not correlated to skeletal morphology. Values of δ¹³C were directly related to zooxanthellae density for all colonies, so that as zooxanthellae concentration increased, δ¹³C valued increased. Colonies maintained under high temperature conditions were offset from the normal, exhibiting ratios less enriched in ¹³C than similar colonies from natural conditions. These trends supported the models of Weber and Goreau in which the carbon pools used in calcification are modified by algal photosynthesis. Direct evidence of physiological differences between symbiotic and asymbiotic colonies of A. danae has also been provided.     

New polymorphic psyllipsocids from Burmese amber (Psocodea: Psyllipsocidae)

Annulipsyllipsocus andreneli gen. et sp. nov. and A. inexspectatus gen. et sp. nov., the first records of the Psyllipsocidae from the Cretaceous amber of Myanmar are described, illustrated and their taxonomic position discussed. The new genus is characterized by antennae with 16 segments; flagellomeres with secondary annulations; radial cell closed, five-angled, bulged on its R1 border; triangular pterostigma. Species belonging to Annulipsyllipsocus gen. nov. are polymorphic. The described taxa represent the earliest evidence for polymorphism in Psocodea. A checklist of all known species of Psyllipsocidae is given.     

Microbial lipids of an intertidal sediment—I. Fatty acids and hydrocarbons

A detailed study has been made of the solvent extractable monocarboxylic, dicarboxylic and hydroxylated fatty acids and n-alkanes in a surface intertidal sediment, and the distributions compared to microorganisms cultured from the sediment. Diatoms are shown to contribute most of the monocarboxylic acids, particularly the significant amounts of polyunsaturated acids present, and a small proportion of the n-alkanes. Bacteria contribute between 11 and 14% of the monocarboxylic acids and markers for this, including trans-monounsaturated acids, are proposed. Detritus from the sea-grass Zostera muelleri is a major source of the α-hydroxy-, ω-hydroxy and α,ω-dicarboxylic acids in the sediment and a minor contributor of n-alkanes and long-chain fatty acids.     

SrCa and MgCa ratios in polygenetic carbonate allochems from a Michigan marl lake

Rapid accumulation of CaCO₃ is occurring in Littlefield Lake, a marl lake located in central Michigan. The sediment, which is 95% CaCO₃, primarily consists of eight different genetic groups of carbonate allochems. These include calcite muds, sands, algal oncoids and Chara encrustations, as well as the dominant aragonitic gastropods Valvota tricarinota. Gyraulus deflectus and Amnicola integra. and the dominant aragonitic pelecypod Sphaerium partumeium. Samples of each of these groups were analyzed for Ca, Sr and Mg. Molar $\text{Mg}\text{Ca}$ ratios are primarily controlled by allochem mineralogy, with calcitic forms having $\text{Mg}\text{Ca}$ ratios 5–10 times larger than aragonitic (shelled) forms. The $\text{Sr}\text{Ca}$ ratios are primarily controlled by biochemical fractionation, and are significantly lower than $\text{Sr}\text{Ca}$ ratios of inorganically precipitated aragonite from other settings. Partition coefficients were determined for both Sr and Mg for each carbonate allochem group and, based on comparisons with results reported by other workers, the partition coefficients determined here are generally considered ‘typical’ or representative values for biogeneous freshwater carbonates. An analysis of variance of the data indicates that most genera and species of carbonate-secreting organisms in marl lakes have highly characteristic $\text{Sr}\text{Ca}$ and $\text{Mg}\text{Ca}$ ratios. These ratios can potentially serve as geochemical tracers in future investigations of lacustrine carbonate diagenesis. Both Sr and Mg are influenced by grain size and/or surface area, probably due to the presence of these elements in non-lattice-held (exchangeable) positions.     

New fossil booklice from the Cretaceous amber of Myanmar (Psocodea: Troctomorpha: Amphientometae: Manicapsocidae)

Palaeomanicapsocus margoae gen. et sp. nov. and Palaeomanicapsocus fouadi gen. et sp. nov. are characterized, described, illustrated, from the Cretaceous Burmese amber. Their phylogenetic position is discussed. These fossil taxa are the first manicapsocid barklice to be described from the Burmese amber.     

Stable hydrogen isotopes in iron oxides—II. DH variations among natural goethites

Goethite samples analyzed for this study have a δD range from ?202 to ?98 per mil with a corresponding δD range of associated waters from about ?110 to +7 per mil. Goethites with the most positive δD values are from marine environments. Goethite-water equilibrium $\text{D}\text{H}$ fractionation factors measured in this laboratory at 100°C and 145°C and estimated for sedimentary temperatures from data on natural samples have values of about 0.900 at all three temperatures. These data suggest that goethite δD values may be a direct, temperature-independent measure of the δD values of the waters with which the goethite last equilibrated. Most of the goethite δD values in this study reflect the δD values of the modern waters in the locales of origin.Substitution of Mn and/or Al for Fe in the goethite structure may affect the mineral-water fractionation factor. Manganese appears to decrease the value of α. The effect of Al substitution on α has not yet been measured, but preliminary arguments suggest that increasing Al content could increase α values.     

A new Burmese amber hawker dragonfly helps to redefine the position of the aeshnopteran family Burmaeshnidae (Odonata: Anisoptera: Aeshnoidea)

The new genus and species Angustaeshna magnifica of Burmaeshnidae is described on the basis of a new fossil from Burmese amber. The genus Cretaeshna from the same amber is transferred from the Telephlebiidae into the Burmaeshnidae. We redefine this last family, no longer considered as the sister group of the Late Cretaceous Enigmaeshnidae, but as putative sister group of the Telephlebiidae in the Aeshnoidea. No known fossil belongs to the Telephlebiidae.     

Comparison of Michigan Basin crude oils

Michigan Basin oils from the Ordovician Trenton, Silurian Niagaran, and Devonian Dundee formations have been geochemically compared by GC, GC-MS, and carbon isotope mass spectrometry. One oil from each formation was selected for detailed analysis which included measurement of individual n-alkane δ¹³C values. The Ordovician and Devonian oils are strikingly similar to one another, yet clearly different from the Silurian oil. This pattern is unexpected because Ordovician and Devonian reservoirs are physically separated by the Silurian strata. From time-temperature considerations, the Devonian oil probably was formed in older strata and has migrated to its present location. Our analyses suggest a common source for the Devonian and Ordovician oils.     

Geochemical distribution of hydrocarbons in sediments from mid-Narragansett Bay,Rhode Island

The concentration of hydrocarbons (saturated and aromatic) and synthetic chlorinated compounds (Chlordane, DDT, and PCBs) decreased with depth in sediment cores from mid-Narragansett Bay and reached background levels at different depths. These depths were in general agreement with those expected based on the chronological inputs of these materials to the Bay. Although the total hydrocarbons concentration decreased with depth, the biogenic n-alkanes (n-C_{25,27,29,31,33}) showed a fairly constant concentration with depth as did the organic carbon content of these sediments. The n-alkane odd/even ratio increased with depth in the cores. Size fractionation (> 45 μm and < 45 to > 0.3 μm) of two core sections showed more hydrocarbons associated with the smaller size fraction in the surface section, while the lower section had approximately equal concentrations in both fractions. These trends suggest that over the time period covered by these cores the inputs of biogenic materials has remained relatively constant, while the input of anthropogenic hydrocarbons has increased dramatically during the last 100 yr. This increase is probably due to the expanded use of petroleum over this time period and subsequent chronic inputs to this estuarine environment.     

The stereoisomeric composition of phytanyl chains in lipids of Dead Sea sediments

Lipid extracts from five recent Dead Sea sediments were analyzed for isoprenoid compounds and the following were isolated: free and phospholipid-bound di-O-phytanylglycerol, free phytanol and free and esterifled phytanic acid. The phytanyl groups of the diether and the free phytanol were oxidized to the corresponding phytanic acid; the stereoisomeric composition of the derived phytanic acids as well as of the ester-bound phytanic acid was determined by open-tubular gas-liquid chromatography of the corresponding methyl esters on butanediolsuccinate polyester. Only the 3R,7R,11R-isomer of phytanic acid was detected in each of the phytanate samples, indicating that these phytanyl chains in the Dead Sea sediments are most likely derived from extremely halophilic bacteria rather than from phytol of chlorophyll origin. These findings also provide further evidence that the mixtures of RRR and SRR-phytanic acids previously isolated from organic-rich shales were most likely derived from the phytyl chain in chlorophyll.     

Stable carbon isotope evidence for two sources of organic matter in coastal sediments: seagrasses and plankton

Organic carbon from sediments collected in Texas seagrass meadows was enriched in ¹³C by an average of 6.6% relative to organic carbon from offshore sediments. Within the South Texas hay system examined. δ¹³C values became increasingly more typical of offshore sediments with increasing distance from seagrass meadows. This permits the use of carbon isotope data as a measure of the relative contributions of seagrasses and plankton to sedimentary organic matter.     

Two new long-legged flies in the Santonian amber of France (Diptera: Dolichopodidae)

Avenaphora gallica sp. nov., second representative of this dolichopodid genus, and Cretomicrophorus piolencensis sp. nov., third representative of this genus, are described from a new lower Santonian amber outcrop in Southern France. The relationships of Avenaphora in the Empidoidea are discussed. Avenaphora gallica and Cretomicrophorus piolencensis were found in a marine littoral swamp palaeoenvironment, as for many modern Parathalassiinae.