Cretaceous trigonioidid (non-marine Bivalvia) assemblages and biostratigraphy in Asia with special remarks on the classification of Trigonioidacea

Non-marine Cretaceous bivalve Trigonioidacea, having an anterior pedal retractor scar distinctly separated from the anterior adductor scar, are subdivided herein into seven families and subfamilies, and 26 genera and subgenera. The general ornament pattern at the family and subfamily level, and features of the radial ribs, including the VA (angle of V-shaped ribs) and hinge teeth at the generic and subgeneric level serve as the basis for classification. They have a wide distribution in Asia, particularly in Middle and East Asia. Seven trigonioidid assemblages are recognized and dated on the basis of morphological features and stratigraphical occurrence of the fossils as well as associated intercalated marine deposits. The seven assemblages are as follows: (1) Hauterivian–Barremian and ?Valanginian Nippononaia (Eonippononaia) tetoriensis–Koreanaia (Eokoreanaia) cheongi–Danlengiconcha elongata assemblage; (2) Late Barremian-Early Albian, but mainly Aptian, Nippononaia (Nippononaia) ryosekiana–Koreanaia (Koreanaia) bongkyuni–Trigonioides (Wakinoa) wakinoensis–Trigonioides (Trigonioides) kodairai–Trigonioides (Trigonioides) quadratus–Plicatounio (Plicatounio) naktongensis–Pseudohyria (Matsumotoina) matsumotoi assemblage; (3) Aptian-Early Albian, but mainly Aptian, Trigonioides (Trigonioides)–Plicatounio (Guangxiconcha) suzukii assemblage; (4) Late Aptian-Early Cenomanian, but mainly Albian, Trigonioides (Diversitrigonioides) diversicostatus–Pseudohyria (Pseudohyria) subovalis assemblage; (5) Albian, probably extending down into Aptian, Trigonioides (Trigonioides) heilongjiangensis bed; (6) Cenomanian, but possibly going up into Turonian, Trigonioides (Trigonioides) paucisulcatus–Trigonioides (Trigonioides) matsumotoi–Trigonioides (Trigonioides) mifunensis–Plicatounio (Guangxiconcha) tamurai assemblage; and (7) Turonian—Early Maastrichtian, but mainly Santonian—Early Maastrichtian, Plicatounio (Plicatounio) hunanensis–Pseudohyria (Pseudohyria) turberculata–Pseudohyria (Pseudohyria) cardiiformis–Pseudohyria (Pseudohyria) aralica assemblage. This biostratigraphy permits correlation and age determination of trigonioidid-bearing formations throughout Asia.     

Chemical oxidation of N,N-diethyl-m-toluamide by sulfate radical-based oxidation: kinetics and mechanism of degradation

A study was undertaken in order to understand the kinetics and mechanism of the chemical oxidation of N,N-diethyl-m-toluamide, an insect repellent, by sulfate radical. In this experiment, sulfate radical was generated using peroxymonosulfate with iron(II) and cobalt(II) as activator. The second-order rate constant for the reaction of the sulfate radical with N,N-diethyl-m-toluamide was found to be (1.9 ± 0.1) × 10⁹ M^?1 s^?1 at pH 7 and a temperature of 25 °C. Experiments for the chemical oxidation of N,N-diethyl-m-toluamide in river water and secondary wastewater revealed that the percentage of the removal of N,N-diethyl-m-toluamide was slightly influenced by the water matrices. However, the selected oxidation systems are not effective for the removal of N,N-diethyl-m-toluamide in seawater. Transformation by-products of N,N-diethyl-m-toluamide generated using peroxymonosulfate/iron(II) sulfate, peroxymonosulfate/iron(II) chloride, peroxymonosulfate/cobalt(II) sulfate and peroxymonosulfate/cobalt(II) chloride systems were identified. The results indicated that there are slight differences in the distributions of the transformation by-products detected depending on the activator. The common transformation by-products detected in all selected oxidation systems are N,N-diethylbenzamide, N-ethyl-m-toluamide, N,N-dimethyl-m-toluamide, N-ethyl-N-acetyl-m-toluamide, 2-(diethylamino)-1-m-tolylethanone, monohydroxylated N-ethyl-m-toluamide, and dihydroxylated N,N-diethyl-m-toluamide. Monohydroxylated N,N-diethyl-m-toluamide were detected only when the peroxymonosulfate/iron(II) system was applied. For the peroxymonosulfate/cobalt(II) systems, additional isomers of monohydroxylated N-ethyl-m-toluamide were detected. Peroxymonosulfate/cobalt(II) also transformed 2-(diethylamino)-1-m-tolylethanone into N-ethyl-N-(2-oxo-2-m-tolylethyl)acetamide and monohydroxylated 2-(ethyl(vinyl)amino)-1-m-tolylethanone as transformation by-products.     

Polar constituents isolated from Green River oil shale

This paper interprets the mass spectrometric, i.r. absorption and NMR data for 22 compounds obtained from a polar fraction of Green River shale. The major constituents analyzed are believed to be of the following compositional types: C_nH_2nO (cyclohexanols and chain isoprenoid ketones), C_nH_2n?10O (tetralones and indanones), C_nH_2n?7N (tetrahydroquinolines), C_nH_2n?11N (quinolines), C_nH_2n?1NO (alkoxypyrrolines), C_nH_2n?5NO₂ (maleimides), C_nH_2n?8 (tetralins), C_nH_2n?12 (naphthalenes) and C_nH_2n?14 (benzylbenzenes). This work expands the present information about nitrogen, oxygen and aromatic constituents indigenous to Green River shale.     

The influence of multiple diffraction on the space group determination of orthopyroxene,spodumene, low omphacite and pigeonite

Forbidden reflections of some pyroxenes described as having a lower symmetry than Pbca or C2/c have been examined, mainly using the detailed ψ-scanning method of the four-circle automated diffractometer. All reflections violating the systematic absences of Pbca orthopyroxene, C2/c spodumene, P2/n omphacite and P2₁/c pigeonite were found to be due to the Umweganregung process of multiple diffraction; the Umweganregung peaks observed for the ψ azimuth were indexed in terms of a four-circle geometry. Thus, the space groups of orthopyroxene, α spodumene, low omphacite and low pigeonite were confirmed to be Pbca, C2/c, P2/n and P2₁/c, respectively.     

Contribution to the biostratigraphy of the Lower Cretaceous in eastern Serbia: Upper Hauterivian Orbitolinidae from the Kamenica 1 section,Kurilovo anticline

Upper Hauterivian deposits in the Kurilovo area, Kamenica 1 section, NE of Niš, are described based of abundant and diverse orbitolinids. So far, the interval was assigned to the Barremian–Aptian on the geological map. Such a new age assignment results from the first detailed study carried out on the orbitolinid fauna contained in the Lower Cretaceous (upper Hauterivian) shallow-water limestones of eastern Serbia. The upper Hauterivian is documented on the basis of two key stratigraphic markers, specifically Valserina primitiva and Paleodictyoconus beckerae.In addition to these late Hauterivian index fossils, the studied section bears orbitolinids having a larger stratigraphic distribution: Cribellopsis neoelongata, Cribellopsis thieuloyi?, Montseciella glanensis, Orbitolinopsis debelmasi, Orbitolinopsis cf. debelmasi, Orbitolinopsis sp., Paleodictyoconus cuvillieri, Paleodictyoconus cf. cuvillieri, Paleodictyoconus cf. beckerae, Paleodictyoconus cf. actinostoma, Paleodictyoconus sp., Paracoskinolina? jourdanensis, Paracoskinolina cf. hispanica, Urgonina alpillensis, Valserina sp. The microfossil assemblage includes other foraminifers such as Charentia cuvillieri, Mayncina bulgarica, Nautiloculina cretacea, Pfenderina globosa, Pseudocyclammina cf. lituus, Pseudolituonella gavonensis, Ammobaculites sp., Bolivinopsis sp., abundant trocholinids, various miliolids, other foraminifers and sparse algae which will be presented separately.     

Stratigraphy and palaeoenvironment of the Lower-“middle” Oligocene units in the northern part of the Western Taurides (İncesu area,Isparta, Turkey)

This study describes the stratigraphic and palaeoenvironmental significance of the Lower-“middle” Oligocene sediments based on the fauna from the Delikarkas? Formation and the microflora from the ?ncesu Formation of the ?ncesu area (northern part of the western Taurides, Isparta province, Turkey). In the area, the Oligocene sediments show a regressive succession, which begins with the limestones of the Delikarkas? Formation indicating marine conditions followed by conglomerates, sandstones and coaly mudstones of alluvial and fluvial (shallow marine-continental) origin. A well preserved foraminiferal assemblage including Nummulites intermedius, Nummulites vascus and Halkyardia maxima proves an Early Oligocene age for the Delikarkas? Formation. Due to palynological markers such as Boehlensipollis hohli, Slowakipollis hippophaëoides, Dicolpopollis kockelii, Magnolipollis neogenicus ssp. minor, Plicapollis pseudoexcelsus, Caryapollenites simplex and Intratriporopollenites instructus the ?ncesu Formation, which concordantly rests on the Delikarkas? Formation, may be assigned to the Early-“middle” Oligocene. From the palynomorph assemblage, three zones have been recognised according to abundance of species. Zone 1 is characterized by predominance of C. simplex and Momipites punctatus and rarely presence of tricolpate and tricolporate pollen. Zone 2 consists mainly of Inaperturopollenites dubius, Leiotriletes maxoides ssp. maximus, Verrucatosporites favus, Verrucatosporites alienus and infrequently marine dinoflagellate cysts. Zone 3 is characterized by a high percentage of ferns such as Echinatisporis?chattensis and Polypodiaceoisporites saxonicus. The presence of marine dinoflagellate cysts like Apectodinium sp. and Cleistosphaeridium sp., back-mangrove elements such as Acrostichum aureum and lepidocaryoid palms (e.g. Longapertites discordis, Longapertites punctatus and Longapertites psilatus) in the sediments of the ?ncesu Formation imply coastal or near-coastal conditions. Terrestrial palynomorphs in more inland settings were transported by running water towards the sea. Conifers are represented by poorly preserved and rare pollen grains of Pityosporites, Cathayapollis and Piceapollis which may have been transported by wind. In this study, the terrestrial climate of the ?ncesu Formation is also discussed on the basis of the Coexistence Approach method. The climate was warm at the coast (over 20 °C), as evidenced by A. aureum and lepidocaryoid palms, whereas there was a mean annual temperature of 17.2–17.4 °C must be assumed for the upland environment(s).     

The effects of pressure and temperature on nonstoichiometric wüstite,FexO: The iron-rich phase boundary

An experimental study using piston-cylinder, Bridgman anvil and diamond anvil cell techniques was undertaken to study the effect of pressure on the composition of Fe _x O in equilibrium with Fe. At constant temperature the value of x first increases and then decreases with increasing pressure. The rate of change of x is a function of temperature. We have theoretically calculated the variation of the composition of wüstite with pressure and temperature. The initial increase of x with pressure for P<10 GPa occurs because the partial molar volume of FeO in Fe _x O is smaller than the molar volume of Fe, favouring an increase in stoichiometry of Fe _x O. To reproduce the experimentally observed decrease in x above 10GPA, the bulk modulus of Fe _x O must vary strongly with x for x?0.96, causing a rapid increase in the partial molar volume of Fe in Fe _x O. Continuation of a strong sensitivity of K to x in Fe _x O for x?0.96, however, leads to absurdly low molar volumes of Fe _x O at high pressure and no equilibrium between Fe and Fe _x O exists. Observations therefore require a reduced sensitivity of K with x for x<0.96, achieved by a negligible variation of K ₀ with x for x<0.96, or a strong variation of dK/dP with x, or perhaps both.     

Seasonal changes in the amphipod fauna ofMicrociona prolifera (Ellis and Solander) (Porifera: Demospongia) and associated sponges in a shallow salt-marsh creek

Between September 1976 and August 1978, samples of four species of sponge,Microciona prolifera (Ellis and Solander),Haliclona loosanoffi Hartman,Lissodendoryx isodictyalis (Carter) andHalichondria bowerbanki Burton, were collected from subtidal shell debris in a North Edisto River, South Carolina saltmarsh creek and associated amphipods identified. Dominant spongicolous amphipods wereColomastix halichondriae Bousfield,Leucothoe spinicarpa (Abildgaard),Corophium simile Shoemaker,Corophium acherusicum Costa,Lembos cf.L. websteri Bate andMelita appendiculata (Say). Densities of amphipods inMicroclona prolifera andHalichondria bowerbanki usually exceeded those inLissodendoryx isodictyalis andHaliclona loosanoffi. Seasonal changes in amphipod dominance were however approximately the same in all sponge species. Winter dominance byCorophium spp., and on occasionLembos spp., is followed by spring dominance byMelita appendiculata and summer dominance byColomastix halichondriae. Harsher winter conditions in 1976–77 apparently resulted in more reduced populations of various sponge species as well asColomastix halichondriae andLeucothoe spinicarpa when compared with the following winter. With some exceptions during the winter, amphipod density inMicrociona prolifera generally decreased as sponge size increased. The range of gammarid amphipod densities inMicrociona prolifera was 128–724 individuals per 5 g (40.3 cm³) of sponge.     

Lacewings (Insecta: Neuroptera) from the Lower Cretaceous Purbeck Limestone Group of southern England

Eight new genera and 12 new species are described from the Lower Cretaceous Purbeck Limestone Group, southern England. Sophogramma wimbledoni sp. nov. (Kalligrammatidae) is described from the Purbeck of Wiltshire. Pterinoblattina peverilensis sp. nov., Pterinoblattina fasciata sp. nov., Purbepsychopsis parallela gen. et sp. nov. (Psychopsidae), Ovalorobius edmondsi gen. et sp. nov. (Prohemerobiidae), Mesosmylidus vulgaris gen. et sp. nov., Osmylochrysa anomala gen. et sp. nov., Osmylochrysa fragilis gen. et sp. nov., Stenochrysa gradata gen. et sp. nov. (Osmylidae), Mesypochrysa minuta sp. nov. (Chrysopidae), Purbemerobius medialis gen. et sp. nov. (?Hemerobiidae), Epimesoberotha parva gen. et sp. nov. (Berothidae) and Pseudocorydasialis alleni (Neuroptera familia incertae sedis) are described from Durlston Bay, Dorset. The species Pterinoblattina penna Scudder, Pterinoblattina pluma (Giebel) (Psychopsidae) Sialium sipylus (Nymphidae) and Osmylopsis duplicata (Osmylidae) are re-examined, described and figured. The genus Valdipsychops Jepson et al. has been synonymized with Pterinoblattina.     

External seismic stability of vertical geosynthetic-reinforced soil walls using pseudo-static method

Analysis of external stability of vertical geosynthetic-reinforced soil (GRS) walls is very important in the seismic prone zone. The scope of this paper is to obtain required minimum reinforcement length, L _min, for external seismic stability of vertical GRS walls by pseudo-static limit equilibrium method. Then, L _min can be calculated to resist sliding, eccentricity, and bearing capacity failure modes. The parameters considered include both horizontal and vertical seismic coefficients (k _h and k _v ), surcharge load (q), wall height (H) and the properties of retained backfill, GRS, and foundation soil. Results show that L _min against sliding failure mode, L _min,S , increases more quickly than that against the other two failure modes with the increase in k _h , q, or unit weight of retained backfill, γ _b , while L _min,S decreases more quickly than that against the other two failure modes with increase in friction angle of retained backfill, ? _b , or unit weight of GRS, γ _r . For the different failure modes, the effect of k _v on L _min is not identical with the change of k _h , and in addition, L _min/H will tend to remain unchanged with the increase in H. In general, L _min against bearing capacity failure mode, L _min,BC, is larger than L _min against the other two failure modes. However, L _min,BC will be less than L _min against eccentricity failure mode, L _min,E , for k _h exceeding 0.35, or friction angle of foundation soil, ? _f , exceeding 37°, and L _min,BC will also be less than L _min,S for friction angle of GRS, ? _r , being no more than 26°.     

Strontium and samarium diffusion in diopside

The volume chemical diffusion of trace amounts of Sr in diopside has been measured as a function of temperature (1100–1300°C), pressure (1 bar–20 kbar), crystallographic direction, and composition. Three experimental/analytical techniques were employed: radiotracer and sectioning; stable tracer and ion microprobe; and Rutherford back-scattering spectroscopy. Comparison of the three yielded excellent agreement. Both natural and synthetic single crystal samples were used with results in the natural diopside giving diffusivities approximately two orders of magnitude greater than those in the man-made crystals. Samarium diffusion in the synthetic crystals was also examined with the ion probe technique with results similar to Sr.Arrhenius relations for diffusion (D = D₀exp[?ΔH_a/RT]) were calculated for different pressures and analytical techniques, and activation volumes (gDV_a) were derived from the equation D = D' exp[?PΔV_a/ RT]. Values of ΔV_a were negative for Sr diffusion. An empirical relation describing the temperature and pressure dependence of D for Sr in the c direction of the synthetic samples is: D(P, T) = 1200 (cm²/sec) exp[?122 (Kcal/mol)/RT (°K)]exp[?P (bar)/(2.94T ? 4640)R]. The expression for D_Sr in the natural samples (c direction) at one atmosphere is: D(0, T) = 54 (cm²/sec) exp[?97 (Kcal/mol)/RT (°K)]. A single compensation trend for all the data was evident for all values of D₀ and ΔH_a in the synthetic crystals.A number of models of geologic processes were investigated in light of the present data. Closure temperatures (T_c) were calculated for examples of mineral-mineral age-dating and trace element geothermometry. High values of T_c indicate that pyroxenes record emplacement events and are generally not disturbed unless a fluid enters the system. Isotopic equilibration times were examined for lower crustal xenoliths and the mantle source region for MORB using the formula of Hofmann and Hart (1978). Equilibration was shown to be too fast for production of isotopic anomalies in MORB via disequilibrium melting. Also. reasonable residence times at lower crustal temperatures were shown to produce the mineralogical-scale isotopic homogeneity observed in a crustal xenolith from Kilbourne Hole, New Mexico.     

Are S–C structures,duplexes and conjugate shear zones different manifestations of the same scale-invariant phenomenon?

By measuring S spacing, C spacing and the S–C angle (α) in deformed rocks, this paper investigates the geometry of previously published examples of S–C and S–C-like structures on a scale range between micrometres and several hundred kilometres. The results indicate that common S–C fabrics of thin-section, hand-specimen and outcrop scale, and conjugate fault/mylonite zones of map scale define a simple function C_spacing=2S_spacing, which depicts a scale-invariant geometry over ten orders of magnitude. Logarithmic plots of cumulative frequency suggest that the S–C fractal set (D=0.13) is restricted to the scale range between 600–800 μm and 1 km where genuine S–C structures, characterized by antithetic shear on the S planes, can be formed. Below 600–800 μm, grain scale processes seem to influence the development of S–C structures. Above the upper limit (1 km), only S–C-like structures with duplex kinematics (synthetic shear on S planes) occur. The S–C and S–C–C′ fractals are envisaged as self-similar structures where the foliations work as both S or C planes, depending on which scale is considered.     

Geometrical classification of multilayered folds

A new classification scheme based on the degree of fluctuation in the geometry of different layers of a multilayered fold is suggested. The classification scheme uses the degree of fluctuation in geometry in terms of the standard deviation (σ_n) of the thickness parameters t_α′ (orthogonal thickness parameter) and T_α′ (axial plane parallel thickness parameter) for n number of layers, and dip angle α. The degree of fluctuation in the geometry of a multilayered fold can be represented by σ_n(t_α′) or σ_n(T_α′) versus α plots on a Cartesian plane. In the proposed classification scheme, multilayered folds have been divided into two broad categories, namely `isodeviatoric' and `anisodeviatoric'. Isodeviatoric folds have a constant fluctuation in the geometry of different layers recorded in terms of σ_n(t_α′) or σ_n(T_α′) for α>10°. A special type of isodeviatoric fold is recognised as `analogous fold' in which each layer exhibits identical geometry [σ<sub>n</sub>(t<sub>α</sub>′) or σ<sub>n</sub>(T<sub>α</sub>′)=0]. Plots of isodeviatoric folds lie parallel to the abscissa (α) and those of analogous folds lie along the abscissa in the σ<sub>n</sub>(t<sub>α</sub>′) or σ<sub>n</sub>(T<sub>α</sub>′) (ordinate) versus α (abscissa) diagram. Analogous folds have been divided into ten varieties (1A1, 1A2, 1A3, 1B, 1C, 2, 3A, 3B, 3C and composite-analogous types). The anisodeviatoric folds do not exhibit constant fluctuation (deviation) in the geometry of different constitutive layers. Such folds have been subdivided into `peri-analogous', `sub-analogous', `sub-non-analogous', `non-analogous' and `strongly non-analogous' types. This classification scheme is applied to folds developed in low-grade metasedimentary rocks of the Mahakoshal Group and low- to medium-grade rocks of the Chhotanagpur Granite Gneiss Complex in central India.     

New data on Upper Kimmeridgian-Tithonian biostratigraphy and ammonites of the eastern Crimea

Based on ammonites, Upper Kimmeridgian sediments are first established in the Crimean Mountains. The Kimmeridgian-Tithonian boundary recognizable in a continuous section is placed inside the Dvuyakomaya Formation of uniform largely clayey sediments. Assemblages of Kimmeridgian ammonites Lingulaticeras cf. procurvum (Ziegler), Pseudowaagenia gemmellariana Oloriz, Euvirgalithacoceras cf. tantalus (Herbich), Subplanites sp.) and Tithonian forms (?Lingulaticeras efimovi (Rogov), Phylloceras consaguineum Gemmellaro, Oloriziceras cf. schneidi Tavera, and Paraulacosphinctes cf. transitorius (Oppel) are described. A new biostratigraphic scheme proposed for the upper Tithonian-Berriasian of the Crimean Mountains includes the following new biostratigraphic units: the Euvirgalithacoceras cf. tantalus Beds of the upper Kimmeridgian, ?Lingulaticeras efimovi Beds of the lower Tithonian, and Oloriziceras cf. schneidi and Paraulacosphinctes cf. transitorius beds of the upper Tithonian. The middle Tithonian is proposed to consist of the fallauxi and semiforme (presumably) zones. The ammonities found determine the early Kimmeridgian-Berriasian age of the Dvuyakornaya Formation that is most likely in tectonic contact with the underlying Khutoran Formation.     

Dynamics of the stationary eddies in the lower stratospheric circulation in the wavenumber domain and monsoon activity

Meridional transports of momentum and sensible heat have been computed using the Fourier coefficients of the geopotential heights at 50 mb and 30 mb levels for each month during the years 1972 to 1979. Seasonal variations in these transports and in the energy conversionsC (K _E ,K _Z ) andC (A _z ,A _E ) in the contrasting years of monsoon activity have been discussed. The transport and the conversion terms undergo annual variations only with winter maxima and summer minima. Large northward transport of momentum and of sensible heat in the low latitude summer and in the high latitude preceeding winter suggests a linkage between monsoon activity and high latitude stratosphere. Seasonal variations in the energy conversion termsC (K _E ,K _Z ) andC (A _Z ,A _E ) conform with the changes in the system in the years of widely differing monsoon activity both in low and high latitudes. Large conversion of energy fromA _Z toA _E in low latitude summer indicates weakening of the existing meridional temperature gradient, in bad monsoon years.     

Endmember graphics

Thek points inp-space corresponding to a specified set ofk (k<p) linearly independent endmember estimates associated with ap-variate (n×p) compositional datasetX, define the vertices of a (k?1) dimensional simplexH. Then estimated mixtures which together account for the systematic variation in the datasetX, are each convex combinations of thek fixed endmember estimates. Accordingly, then-points inp-space which represent these mixtures must be interior points of the simplexH. The purpose of this paper is to describe a simple graphical procedure for examining the positions of the estimated mixtures relative tok=3 or 4 putative endmembers, and for assessing their compliance or otherwise with the convexity constraints. Since the mixture coefficients must be estimated first in order to obtain the mixture estimates, the paper begins with a review of the least-squares partitioning procedure.     

New collectors for sphalerite flotation

A series of N-arylhydroxamic acids (31) were synthesized and tested as collectors to float sphalerite from a Canadian copper–zinc ore. The compounds were classified into four types namely, N-aryl-C-alkyl, N-aryl-C-aryl, N-aryl-C-aralkyl, and dihydroxamic acids based on the type of substitution. Dihydroxamic acids were found to be poor mineral collectors while the efficiency of sphalerite flotation increased in the order N-aryl-C-aryl < N-aryl-C-alkyl < N-aryl-C-aralkyl. Sphalerite was floated without activation by copper sulfate, and the best sphalerite recovery of about 80% (grade 32%) was achieved with N-hydrocinnamoyl-N-phenylhydroxylamine (HCNPHA) 67 g/t collector dosage. However, pyrite also floated along with sphalerite and this appeared as a major disadvantage to be addressed.     

Solubility and complexing of Ni in the system NiO-H2O-HCl

The solubility of bunsenite (NiO) in Cl-bearing fluids in the range of 450°–700°C, 1–2 kbar was determined using the Ag + AgCl acid buffer technique. Based on the results of the experiments, it is concluded that the associated NiCl⁰₂ complex is the dominant Ni species in the fluid over the entire temperature-pressure range investigated. The temperature dependence of the equilibrium constant for the reaction NiO(s) + 2HCl⁰(aq) = NiCl⁰₂(aq) + H₂O is given by logK = ?4.17(±0.55) + 4629(±464)/T(K) at 1 kbar, and logK = ?4.75(±0.91) + 5933(±756)/T(K) at 2 kbar. The calculated difference in standard state Gibbs free energy of formation between NiCl⁰₂ and 2HCl⁰ in kcal is G⁰(NiCl⁰₂) ? 2G⁰(HCl⁰) = ?20.77(±2.22) + 0.03264(±0.0026)T(K), at 1 kbar and G⁰(NiCl⁰₂) ? 2G⁰(HCl⁰) = ?25.01(±1.35) + 0.03264(±0.0016)T(K) at 2 kbar. Comparison of the solubilities of Ni end-member minerals with those of Ca, Mn, Fe, and Mg indicates that nickel minerals generally are the least soluble at a given temperature and pressure. The relatively low solubility of Ni end-member minerals, combined with the relatively low concentration of Ni in most rocks, should result in a quite low mobility of Ni in hydrothermal fluids.     

Refractive index and compressibility of Di64An36 glass over a pressure range of 0–5.0 GPa

Data on the refractive index, density, and bulk modulus variations of Di₆₄An₃₆ glass, which is used as a model basalt melt, were obtained with a polarization interference microscope and a high-pressure diamond anvil cell at ambient temperature and pressure up to 5.0 GPa. An anomalous decrease in the bulk modulus, K _t , was observed in the pressure range 0?C1.0 GPa. The values of the zero-pressure isothermal bulk modulus, K _t,0 = 22.2, and variation of the bulk modulus with pressure, ??K _t /??P = 11.35, were derived using a linear equation relating K _t and P over the pressure range with the normal behavior of the compressibility. A comparison of our results with previous data on other glasses and melts showed that the bulk moduli of silicate glasses are similar to those of corresponding melts. The values of the pressure coefficient of the bulk moduli, ??K _t /??P, for glasses derived from linear equations are 2.5 times higher than the pressure derivative of the bulk modulus, K?? _T , derived using the Birch-Murnaghan equation for corresponding melts. The difference in ??K _t /??P and K?? _T has an effect on the compressibility of glasses and melts. The compressibility of glasses up to 5.0 GPa calculated as (d ? d ₀)/d is almost two times lower than that of corresponding melts.