Hawaiian volcanic propagation and Hawaiian swell asymmetry: evidence of northwestward flow of the deep upper mantle

Bathymetry and the geoid anomaly of the northern flank of the Hawaiian swell is broader and higher than the southern flank, and it is characterized by higher heat flow than the axis or southern flank. It is here proposed that the northern flank of the Hawaiian swell has been augmented by heat conducted from the hotspot conduit into the upper mantle then transported northward of the volcanic axis by flow in the upper mantle (325°) that is more northerly than Pacific plate motion (292°). By assuming that the deep upper mantle is decoupled from the Pacific plate and is flowing at 325° to the northwest, changes in direction and rate of volcanic propagation and in geochemistry along individual volcanic segments of the Hawaiian volcanic chain can be interpreted in terms of tank experiment results showing that a volcanic hotspot conduit breaks into diapirs when tilted by mantle flow. Hawaiian volcanoes are aligned in en-echelon segments, and the Hawaiian Islands are the two most recent segments. For an individual segment, older northwestern volcanoes are aligned nearly parallel to the 292° plate motion direction, and they propagated to the southeast at approximately the same rate as the 92 km/m.y. speed of northwestward plate motion. In contrast, the alignment of the younger southeastern volcanoes is close to 325°, and they show a conspicuous acceleration in propagation of volcanism marked by out-of-sequence eruptions. Within the model proposed here, diapirs rise from instability nodes that develop along the tilted conduit of a mantle hotspot plume as it is sheared in the direction of deep upper-mantle flow and each diapir gives rise to a single volcanic center. As tilting progresses, diapirs form at lower levels along the conduit in more upstream positions of the mantle flow zone, rise sequentially into the decoupled lithosphere, erupt sequentially, and are translated in the direction of plate motion (older, northwestern Hawaiian Islands). Eventually, flow in the highly tilted conduit is impeded to the degree that the remaining upstream conduit breaks into a number of diapirs that rise together into the lithosphere. These late diapirs, translated as a group aligned in the direction of horizontal mantle flow, erupt over a relatively short time span and show out-of-sequence volcanism (younger, southeastern Hawaiian Islands). At this stage, a new cycle of rising and tilting will initiate the next en-echelon segment.     

Gas chromatographic/mass spectrometric (GC/MS) analysis of C27–30-steranes

Sterane analyses in petroleum geochemistry are normally based on mass spectrometric detection of major fragment ions. This method has limited specificity and is much improved by detection of parent or metastable transition ions. The latter provide a less complex picture and suggest a better analytical approach, although the technique has only limited mass resolution.Geochemical parameters calculated from mass spectrometric data are dependent on the method employed. Accepted values of these parameters will, therefore, show some variations with the techniques used.Internal standards are necessary for quantitative determination of components by mass spectrometry. A recommended approach is to use a stable isotope labelled analogue of the compound being determined with, in the case of deuterium, only three or four isotopic atoms introduced into the molecule. Too few isotopic atoms will result in interference from the natural isotopes and too many will give analytical deviations.     

Importance of volcanic glass alteration to sediment stabilization: offshore Japan

A minor amount (ca 1 wt%) of amorphous silica cement sourced from volcanic glass inhibits consolidation of hemipelagic sediment approaching the Nankai Trough subduction zone throughout the Shikoku Basin. The distribution and nature of the cement were examined via secondary and backscattered electron imaging. The amorphous silica occurs as altered material in contact with volcanic glass, coating grains (including grain contacts) and filling pores. Based on chemical and petrographic evidence, the cement is probably sourced from volcanic glass; this is in contrast to a previous suggestion that this silica cement is sourced dominantly from biogenic silica. Amorphous silica sourced from disseminated volcanic glass shards has the ability to form a thin coating on clay‐dominated sediment throughout the Shikoku Basin. Measured amorphous silica content in hemipelagic sediments suggests that the cementing process is active throughout the Shikoku Basin (at sites separated by >500 km). The cementation process may occur in other locations where sediment containing hydrated disseminated volcanic glass is buried sufficiently for heat to facilitate alteration (i.e. Central America, Cascadia and the Gulf of Alaska).     

A method for determination of volcanic glass concentrations in sedimentary sequences and its application to quaternary studies

A method for determination of volcanic glass concentration in sedimentary sequences is presented. This method consists of two steps: (1) systematic extraction of volcanic glass particles from samples taken at close intervals in a sedimentary section, and the determination of their concentration; (2) precise measurement of the refractive indices of the separated glass particles. A recently developed measuring system (RIMS 86) based on the thermal immersion method permits quick and accurate measurement of the refractive index of a large number of grains within samples. Based on these kinds of data, we typically recognize five types of concentration of volcanic glass shards in sedimentary sequences. The method proposed here enables the simultaneous determination of the refractive index of glass shards and the proportion of glass shards in a sample, which makes it possible to recognize certain ash-fall-horizons, even those undetectable through visual observation of a sedimentary column. © 1994 John Wiley & Sons, Inc.     

Thermochemical redox equilibria of ZoBell's solution

The redox potential of ZoBell's solution, consisting of $\text{3.33 × 10}{}^{\mathrm{?3}}$ molar K₄Fe(CN)₆, $\text{3.33 × 10}{}^{\mathrm{?3}}$ molar K₃Fe(CN)₆ and 0.10 molar KCl, has been measured by a polished platinum electrode vs a saturated KCl, Ag/AgCl reference electrode. Measurements in the temperature range 8–85°C fit the equation $\text{E(}\text{volts}\text{) = 0.23145 ? 1.5220 × 10}{}^{\mathrm{?3}}\text{(t ? 25) ? 2.2449 × 10}{}^{\mathrm{?6}}\text{(t ? 25)}{}^2$ where $\text{t}$ is in degrees Celsius. Evaluation of literature data was necessary to obtain a reliable value for the Ag/AgCl half-cell reference potential as a function of temperature. Combining the measurements from this study with the literature evaluation of the Ag/AgCl reference potential yields the temperature dependent potential for ZoBell's solution: $\text{E(}\text{volts}\text{) = 0.43028 ? 2.5157 × 10}{}^{\mathrm{?3}}\text{(t ? 25) ? 3.7979 × 10}{}^{\mathrm{?6}}\text{(t ? 25)}{}^2$ relative to the standard hydrogen potential. From these data the enthalpy, entropy, free energy and heat capacity for the ferro-ferricyanide redox couple have been calculated. The temperature equation for the potential of ZoBell's solution may be used for checking potentiometric equipment in the determination of the redox potential of natural waters.     

High Precision Thermal Ionization Mass Spectrometric Dating of Corals and Its Application to Paleo—Environmental Study

Global change has become a hot spot in Quaternary geology,and high-precision,high-sensitivity dating is also an urgent problem which needs to be solved.This paper presents some achievements in U-servies dating of marine corals by thermal ionization mass spectrometry (TIMS) and its application to the study of paleo-environments.Recently,coral samples were determined for their ages on a MAT-262 mass spectrometer and satisfactory results have been obtained.     

Chemical balance of the Earth's crust

The chemical composition and lithologic proportions of average sedimentary and igneous rocks are analyzed by a linear least squares regression. The best set of internally consistent data for sediments in geosynclines, continental platforms, deep ocean basin and the average igneous and sedimentary rock are shown below. These results are based on published estimates of the chemical composition of igneous and sedimentary rocks and the relative volume of sediments on the continents and in the deep ocean basins.

$\text{SiO}{}_2\text{A1}{}_2\text{O}{}_3\text{Fe(total)}\text{MgO}\text{CaO}\text{Na}{}_2\text{O}\text{K}{}_2\text{O}\text{CO}{}_2\text{Geosynclines}\text{55.2}\text{12.0}\text{3.6}\text{3.2}\text{8.3}\text{1.0}\text{2.4}\text{8.6}\text{Platforms}\text{49.5}\text{10.7}\text{3.2}\text{3.3}\text{12.3}\text{0.9}\text{2.2}\text{10.8}\text{Av. sed.}\text{55.9}\text{13.8}\text{4.4}\text{3.6}\text{5.8}\text{1.2}\text{2.6}\text{5.2}\text{Av. ig.}\text{59.0}\text{15.0}\text{5.0}\text{3.6}\text{7.0}\text{3.4}\text{3.2}$

The lithologic proportions are: geosyncline—24% sandstone, 58% shale, and 16% carbonate; platform—23% sandstone, 49% shale and 26% carbonate; average sedimentary rock—13% sandstone, 33% shale, 12% carbonate, and 41% pelagic; average igneous rock is approximately 2/3 granodiorite and 1/3 tholeiite. These data indicate a chemical balance of major elements in the Earth's upper crust during the last 1.5 b.y.     

The roving palate: North America's ethnic restaurant cuisines

Although patterns of food consumption, and foodways in general, have profound social, cultural and economic implications, geographers and other social scientists have accorded the topic minimal attention. By examining the identity, number and location of restaurants in the United States and Canada offering self-consciously ‘ethnic’ and regional cuisines, i.e. a form of gastronomic tourism, to largely non-ethnic and extra-regional patrons, we can begin to explore the shifting connotations of ethnicity and the general transnationalization of culture in recent years, as well as changing food preferences. The information available in classified telephone directories for 271 metropolitan areas (the SMSAs of the U.S. and their Canadian equivalents) enables us to chart the larger outlines of the North American ethnic restaurant scene ca. 1980. Analysis of all recent Pennsylvania directories and those of Philadelphia over the period 1920–1980 provides insight into the nonmetropolitan and historical dimensions of the phenomenon. Ethnic restaurant cuisines are now both quite numerous and widespread throughout the continent, and contain dietary items from virtually all the many immigrant groups present, be they major or minor. But the incidence of the cuisines relative to total number of inhabitants or restaurants varies greatly among regions and by category of metropolis. Furthermore, there is usually at best only a weak relationship between the geographic pattern of a given cuisine and that of the related immigrant stock. On the other hand, socioeconomic class, regional culture and volume of affluent visitors seem to be significant determinants. Of special interest are the patterns for the three dominant cuisines, Chinese, Italian and Mexican, and their variants, and the two most important élite cuisines, the French and Japanese.     

Isotopic and elemental abundances of copper and zinc in lunar samples, Zagami, Pele’s hairs, and a terrestrial basalt

We used ICP–MS to measure the elemental concentrations and isotopic abundances of Cu and Zn in: nine Ti-rich lunar basalts (10017, 10022, 10024, 10057, 70215, 71055, 74255, 75055, and 75075); size-separated samples prepared by sieving of pyroclastic black glass 74001, orange glass 74022, and the lunar soils 15021, 15231, 70181, and 79221; a basalt from the Piton des Neiges volcano, Reunion Island; two samples of Pele’s hairs from the Nyiragongo volcano, Democratic Republic of Congo, and the martian meteorite Zagami.The isotopic fractionation of zinc in lunar basalts and Zagami is mass dependent relative to a terrestrial standard (JMC 400882B). These and published results imply that lunar, terrestrial, meteoritic, and perhaps martian zinc all come from one or more reservoirs linked by mass-dependent fractionation processes. Relative to terrestrial basalts, Ti-rich lunar basalts are enriched in the heavier isotopes of Cu and Zn: we find for Ti-rich lunar basalts the following ranges and averages ±1 − σ (‰): δ⁶⁵Cu/⁶³Cu ≡ δ⁶⁵Cu, 0.1–1.4, 0.5 ± 0.1‰ (N = 7); δ⁶⁶Zn/⁶⁴Zn ≡ δ⁶⁶Zn = 0.2–1.9, 1.2 ± 0.2‰ (N = 8; 10017 excluded). For two terrestrial samples, we find δ⁶⁶Zn  +0.3‰ and δ⁶⁵Cu  0‰, which are consistent with published values. The differences between the lunar basalts and terrestrial basalts could reflect minor, planetary-scale vaporization or igneous processes on the Moon.Data for size separates of the pyroclastic glasses 74001 and 74220 confirm the well-known surface correlation of Cu and Zn, but modeling calculations reveal no sharp differences between either the elemental ratios or the isotopic composition of grain interiors and exteriors. The absence of such differences indicates that the isotopic compositions for bulk samples are dominated by a light-isotope-rich surface component.Data for size separates of lunar soils also confirm the surface correlation of Cu and Zn, but an enrichment of heavy rather than light isotopes. Averages for bulk lunar soils from this work and the literature are (‰): δ⁶⁵Cu, from 1.4 to 4.1, average 3.0 ± 0.3 (N = 9); δ⁶⁶Zn, from 2.2 to 6.4, average 4.0 ± 0.3 (N = 14). As with the glasses, in all but soil 15231 our data show no strong differences between the isotopic composition of soil sub-samples with small and large grains.The size of the isotopic fractionation inferred for the surface component in the soils is 3× smaller than predicted by a published model of sputtering primarily by solar particles. At the same time, the observed fractionation is larger than predicted by calculations based on a model of micrometeorite impact heating and hydrodynamic quenching. Because impact heating appears unable to explain the observations, we conclude that sputtering must be important even though samples with very large isotopic fractionation of Cu and Zn have not yet been found.     

Atmospheric trace metals: global cycles and assessment of man's impact

Global data are presented for sources of atmospheric input for 20 trace metals, and the relative importance of natural and anthropogenic sources is assessed. Interference factors are calculated as (total anthropogenic emissions/total natural emissions) × 100. For lithophile metals such as Fe and Mn, interference factors are small. In contrast, the atmophile metals, such as As, Se and Hg, exhibit large interference factors. A significant degree of correlation exists between interference factors and enrichment factors, where enrichment factor is defined as the metal/Al ratio in atmospheric particulates divided by the metal/Al ratio in soils. For many of the trace metals, enrichment factors are of the same order of magnitude at high latitudes in both the Northern and Southern Hemispheres, and are larger at high latitude than at mid latitude.A simple mathematical model is used to calculate present-day enrichment factors in both hemispheres based on natural and anthropogenic influxes, effluxes, and transfer between hemispheres. The calculated enrichment factors are in good agreement with the observed enrichment factors for lithophile metals at both mid and high latitude, and for atmophile metals at mid latitude. However, calculated enrichment factors for atmophile metals are lower than observed enrichment factors at high latitude. To explain these results, we propose that for Hg, As and Se, and perhaps for other atmophile metals, there are significant fluxes from the sea surface to the atmosphere. If the estimated low-temperature fluxes of As, Se and Hg from the land and sea surfaces are included in the interference factor calculations for these metals, the factors are reduced to less than 100%.     

Standard chemical‐based tephra extraction methods significantly alter the geochemistry of volcanic glass shards

The chemical compositions of tephra shards are widely utilised in a myriad of disciplines, including volcanology, petrology, tephrochronology, palaeoecology and climate studies. Previous research has raised concerns over the possible chemical alteration of microscopic (<100 µm) volcanic glass shards through standard extraction procedures, such as the widely used acid digestion method. This study subjects 10 samples of well‐characterised volcanic glasses ranging from basalt to rhyolite to three common methods used in the extraction of volcanic material from lake sediments and peats. The major element geochemistry of each sample was analysed and compared with a control group. The results of this test indicate that basaltic and andesitic glasses are highly susceptible to chemical alteration, particularly to the concentrated corrosive materials used in acid and base digestion techniques. PERMANOVA analysis of the variation within groups suggests that the oxides most susceptible to variation are alkalis from groups I and II (K₂O, Na₂O, CaO, MgO) and SiO₂, and the most stable oxides are Al₂O₃ and FeO. Felsic glasses are considerably less susceptible to alteration by both acidic (HCl, HNO₃, H₂SO₄) and alkaline (KOH) digestions. Our findings have important implications for interpreting the geochemistry of volcanic glasses. Copyright © 2019 John Wiley & Sons, Ltd.     

Numerical models of convection in the earth's mantle

Calculations on convection in Newtonian fluids at large Rayleigh numbers show behaviour in general agreement with geophysical observations. The calculated values of surface velocities, regional gravity and topographic anomalies all lie within the range of values found at the earth's surface. The sign of the gravity anomaly over rising fluid is positive because the gravitational effect of the surface deformation is greater than that of the density deficit. This result appears to agree with geophysical observations and should permit the flow within the mantle to be followed in some detail.     

Local labour market analysis: It's importance and a possible approach

This paper, written from a British perspective, presents a case for more local, as opposed to regional, economic research and argues for the central importance of the local labour market. Such research should direct its attention to the employment decision making of employers and employees. Alternative definitions of the local labour market are discussed, favouring that of M.W. Smart as the most appropriate. The importance of corporate spatial structure, and the labour force adjustment methods available to individual firms faced with declining product demand are discussed. Finally, a possible approach to local labour market analysis is outlined, based on the use of company personnel records.     

Man's impact on shorelines and nearshore environments: a geomorphological perspective

Man evolved late in terms of geologic history, yet he has become a major geomorphologic agent despite his short tenure on Earth. His ability to alter the materials, processes and forms along the world's shorelines are manifested in a variety of ways. Beginning with the indirect changes that resulted from early agriculture and animal husbandry, he progressed to direct modification through reclamation and harbor construction. Today, in the name of shoreline stabilization, thousands of kilometers of natural shoreline have been modified by the addition of artificial structures.     

Chemical composition and origin of the earth's primitive mantle

An attempt has been made to estimate the chemical composition of the earth's primitive mantle by a critical evaluation of data derived from ultramafic mantle samples and partial melting model calculations for mafic and ultramafic magmas of various ages.Compatible (Al, Ca, Si, Mg, Fe) and moderately incompatible (Ti, Zr, heavy and middle rare earth) elements in basaltic magma sources have not changed significantly since the early Archaean (~3.5 Byr). Estimated abundances for refractory lithophile elements (such as Al, Ca, Ti, Zr, Y, Se, REE etc.) in the primitive mantle are about 2.0 times ordinary chondrites (~ 1.1 times Cl chondrites relative to Mg). Highly incompatible volatile elements (K, Rb, Cs, Tl, Pb etc.) are depleted in the mantle throughout geological time. Abundances of Fe, Ni and Co are obtained on the basis of values for ultramafic nodules and model calculations using komatiites of various ages. The results show little (? 20%?) dispersion and there is no obvious secular variation since 3.5 Byr. Noble metals show similar effects. These data permit constraints to be placed on the timing of core formation.The estimated elemental abundances for the primitive mantle are normalized to Cl chondrites relative to Mg and plotted against the solar condensation temperature at 10^?4 atm. Above 700 K there are two parallel trends which are defined by lithophile elements (Al, Ca, REE, Ti, Mg, Si, Cr, Mn, Na, K, Rb, F, Zn etc.) and siderophile elements (W, Ni, Co, P, As, Ag, Sb and Ge) respectively. The depletion factor for the siderophile trend relative to the lithophile trend is about 0.085. Within each trend there is a continuous depletion towards lower temperature. A third trend is defined by noble metals (Ir, Os, Re, Pd, Pt and Au) with a depletion factor of about 0.003 relative to Cl chondrites. These trends are interpreted in terms of core-mantle differentiation and volatility-controlled processes operating before and during earth accretion.     

The neighbourhood effect won't go away: Observations on the electoral geography of England in the light of Dunleavy's critique

Many studies of British electoral geography suggest that class is the major influence on voting patterns, with the neighbourhood effect presented as an ‘explanation’ for variations around the class cleavage. Recently Dunleavy has criticised this model. Analyses undertaken in the light of his critique find clear patterns of inter-constituency variation in voting that are consistent with the neighbourhood effect.     

Chemical equilibration of the Earth's core and upper mantle

The oxygen fugacity (fO₂) of the Earth's upper mantle appears to lie somewhat above that of the iron-wüstite buffer, its fO₂ is assumed to have been similar to the present value at the time of core formation. In the upper mantle, the Fe-rich liquid protocore that would form under such conditions of fO₂ at elevated temperatures would lie predominantly in the system Fe-S-O. Distribution coefficients for Co, Cu, Ni, Ir, Au, Ir, W, Re, Mo, Ag and Ga between such liquids and basalt are known and minimum values are known for Ge. From these coefficients, upper mantle abundances for the above elements can be calculated by assuming cosmic abundances for the whole Earth and equilibrium between the Fe-S-O protocore and upper mantle. These calculated abundances are surprisingly close to presently known upper mantle abundances; agreements are within a factor of 5, except for Cu, W, and Mo. Therefore, siderophile element abundances in the upper mantle based on known distribution coefficients do not demand a late-stage meteoritic bombardment, and a protocore formed from the upper mantle containing S and O seems likely.As upper mantle abundances fit a local equilibrium model, then either the upper mantle has not been mixed with the rest of the mantle since core formation, or else partition coefficients between protocore and mantle were similar for the whole mantle regardless of $\text{P}$, $\text{T}$, and fO₂. The latter possibility seems unlikely over such a $\text{P-T}$ range.