XRF AND INAA DETERMINATIONS OF MAJOR AND TRACE ELEMENTS IN GEOLOGICAL SURVEY OF JAPAN IGNEOUS AND SEDIMENTARY ROCK STANDARDS

Major and trace element analyses have been obtained by wavelength dispersive X-ray fluorescence for the Geological Survey of Japan Igneous rock series and selected samples from the Sedimentary rock series reference samples. Additional trace element data for the Igneous rock series were obtained by instrumental neutron activation analysis. Samples were analyzed multiple times for 10 major elements (with loss-on-ignition) and the following trace elements; As, Ba, Ce, Co, Cr, Cs, Cu, Eu, Ga, Hf, La, Lu, Nb, Nd, Ni, Pb, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, U, V, W, Y, Yb, Zn and Zr.     

Tertiarisation and socio-spatial differentiation in Wales

Processes of economic restructuring and social recomposition have been proceeding at an accelerated pace in Wales of late. This paper seeks to show that these changes, which began with a redistribution of manufacturing employment initially, but which have more recently been dominated by the restructuring of the tertiary sector, can best be understood as a regional effect of the growing spatial division of labour in the UK and internationally. Of special interest is the manner in which the dual spatial divisions in secondary and tertiary economic activity produce new combinations of spatial and social differentiation at the sub-regional level.     

Tephra layers in the Byrd Station ice core and the Dome C ice core, Antarctica and their climatic importance

Volcanic glass shards from tephra layers in the Byrd Station ice core were chemically analyzed by electron microprobe. Tephra in seven layers have similar peralkaline trachyte compositions. The tephra are believed to originate from Mt. Takahe, on the basis of their chemical similarity to analyzed rocks from Mt. Takahe and because dated rock samples from the volcano are younger than 250,000 years old. Glass shards from 726 m deep in the Dome C ice core, which is 2400 km from Byrd Station, are composed of peralkaline trachyte and may have also been derived from Mt. Takahe. The tephra could have resulted from eruptions which were triggered by increased ice loading during the late Wisconsin glaciation. Preliminary grain size data suggest the eruptions were only minor and they were unlikely to have instantaneously altered global climate as have explosive eruptions in the tropics. Nevertheless, the effect of this localized volcanic activity upon the Antarctic energy budget warrants further investigation.     

The Rio Grande fracture zone in the western South Atlantic and its tectonic implications

A broad zone of linear, mappable basement structures is observed north and northeast of the Rio Grande Rise in the South Atlantic Ocean. These structures lie along the same flow line as the Sa?o Paulo Ridge, the Florianopolis High, and onshore lineaments, suggesting that they all comprise the same tectonic trend: the Rio Grande fracture zone. The morphology developed along this fracture zone during the early opening of the South Atlantic Ocean formed a barrier to open ocean circulation during the Aptian and allowed the formation of extensive evaporite deposits to the north of it.     

Origin of Archean migmatites from the Gwenoro Dam area,Zimbabwe-Rhodesia

Archean migmatites in the vicinity of Gwenoro Dam in Zimbabwe-Rhodesia are composed chiefly of trondhjemite gneiss (TR), mafic tonalite (MT), amphibolite (AM), leuco-trondhjemite veins (LTR), and pegmatites. The gneiss is intruded in nearby areas with small tonalite plutons (TN). Geochemical model studies together with field relationships are consistent with the following model for migmatite production: AM is produced by partial melting of a partly depleted ultramafic parent in which neither garnet nor amphibole remain in the residue; TR and TN are produced by partial melting of undepleted to variably depleted amphibolite in which garnet does not remain in the residue; MT is produced by mixing of plagioclase-rich TR with AM; and LTR represents the solid residue after fractional crystallization of TR.     

Fe2+ -F avoidance in silicates

Fe²⁺-F avoidance, reported in the literature in micas and amphiboles, can be accounted for by crystal field theory. The crystal field splitting parameter, Δ_O, of Fe²⁺ octahedrally coordinated to F^? is significantly smaller than its value when (OH)^? is the coordinating anion. Thus, the presence of Fe²⁺ is not favored at sites where F^? substitutes for (OH)^? due to smaller crystal field stabilization energy.     

Toxic dinoflagellates and tidal power generation in the Bay of Fundy,Canada

The incidence of Paralytic Shellfish Poisoning along the eastern seaboard of America has increased and spread during the last decade. One of the core areas for Paralytic Shellfish Poison (PSP), a poison that is derived from toxic dinoflagellates, is centred on the Bay of Fundy. It is in the upper reaches of the Bay of Fundy that a proposal has been made to construct a tidal power generation plant; this project would have a considerable effect on the water circulation, tidal regime and sedimentation characteristics of the Bay of Fundy and Gulf of Maine. Alterations such as these to the hydrography of this area may lead to changes in the occurrence of toxic dinoflagellates and the associated patterns and intensity of PSP.     

Estimating the Surface Wind Speed Over Drifting Pack Ice from Surface Weather Charts

Routine surface wind speed data, vital for the study of drifting pack ice, are not available for the polar oceans. Over sea, it has been demonstrated by Hasse that estimates of surface wind speed may be obtained from the geostrophic wind speed using linear formulae. Comparing estimated with observed data for six sites in Canada, it is found that the formulae may also be applied to obtain estimates of surface wind speed over pack ice.     

Fatty acids and hydrocarbons in surficial sediments of Lake Huron

Fatty acid and hydrocarbon distributions in surficial sediments from ten locations in southern Lake Huron indicate both aquatic and terrigenous recent biological sources of these geolipid materials. Normal alkanoic acids appear to be derived primarily from aquatic sources whereas normal alkanes are from multiple origins. Geolipid distributions are determined by the nature of the biogenic source and are modified during transport and deposition. Sediments receiving urban runoff in Saginaw Bay contain large amounts of non-biogenic hydrocarbons of a petroleum or industrial nature.     

The mineralogy and petrology of manganese-rich rocks from St. Marcel,Piedmont, Italy

Manganese-rich metamorphic rocks containing violan from St. Marcel, Piedmont, Italy formed under blueschist facies conditions, yielding an unusual suite of minerals including omphacite-albite-quartz, braunite, microcline, hollandite, piedmontite, and strontian calcite. Violan, a violet-colored pyroxene, is shown to be a manganoan omphacite having a primitive unit cell, and is found in the same sample as diopside, possibly indicating a solvus relation. A manganoan phlogopite and a celadonitic muscovite coexist in one sample with microcline. The occurrence of celadonite and phlogopite is the first from the blueschist facies and the celadonite component in the dioctahedral mica is buffered at a maximum by coexistence with phlogopite, microcline, and quartz. Various phase relations are used to establish the P and T of equilibration at 8±1 kbar and 300±50 °C, respectively, while the oxygen fugacity is shown to have been very high, for these temperatures, as consistent with braunite+quartz and the presence of piedmontite. Contribution No. 343, from the Mineralogical Laboratory, Department of Geology and Mineralogy, The University of Michigan, Ann Arbor, MI 48109, USA