Density and conductivity properties of Na−CO3−Cl−SO4 brine from Mono Lake, California, USA

Relationships among conductivity, temperature, total dissolved solids (TDS), and density were determined for hypersaline brine (TDS, 83 g kg⁻¹) from Mono Lake. A theoretical estimate of density based on ionic composition and calculated partial molar volumes compared well with actual measurements (difference, 390 ppm). However, an empirically derived equation of state based on temperature and conductivity provides the most accurate density estimates (residual errors, 190 ppm) and can be used with data collected with CTD profilers.     

Darkness on the Edge of Town: Mapping Urban and Peri-Urban Australia Using Nighttime Satellite Imagery

This article explores the use of nighttime satellite imagery for mapping urban and peri-urban areas of Australia. A population-weighted measure of urban sprawl is used to characterize relative levels of sprawl for Australia's urban areas. In addition, the expansive areas of low light surrounding most major metropolitan areas are used to map the urban–bush interface of exurban land use. Our findings suggest that 82 percent of the Australian population lives in urban areas, 15 percent live in peri-urban or exurban areas, and 3 percent live in rural areas. This represents a significantly more concentrated human settlement pattern than presently exists in the United States.     

Adding the missing third and fourth dimensions to trajectory analysis in carbonate systems

We developed a seismic geomorphology-based procedure to enhance traditional trajectory analysis with the ability to visualize and quantify lateral variability along carbonate prograding-margin types (ramps and rimmed shelves) in 3D and 4D. This quantitative approach analysed the shelf break geometric evolution of the Oligo-Miocene carbonate clinoform system in the Browse Basin and delineated the feedback between antecedent topography and carbonate system response as controlling factor on shelf break rugosity. Our geometrical analysis identified a systematic shift in the large-scale average shelf break strike direction over a transect of 10 km from 62° to 55° in the Oligo-Miocene interval of the Browse Basin, which is likely controlled by far-field allogenic forcing from the Timor Trough collision zone. Plotting of 3D shelf break trajectories represents a convenient way to visualize the lateral variability in shelf break evolution. Shelf break trajectories that indicate contemporaneous along-strike progradation and retrogradation correlate with phases of autogenic slope system re-organization and may be a proxy for morphological stability of the shelf break. Shelf break rugosity and shelf break trajectory rugosity are not inherited parameters and antecedent topography does not dictate long-term differential movement of the shelf margin through successive depositional sequences. The autogenic carbonate system response to antecedent topography smooths high-rugosity areas by filling accommodation and maintains a relatively constant shelf break rugosity of ~150 m. Color-coding of the vertical component in the shelf break trajectory captures the creation and filling of accommodation, and highlights areas of the transect that are likely to yield inconsistent 2D sequence stratigraphic interpretations.     

Urban settlement size trends in the former USSR: 1970-1989

"Based upon recently published data, this paper investigates urban settlement size trends in the former USSR and its republics during the intercensal periods of 1970-1979 and 1979-1989. Results indicate that although a trend toward largeness of the Soviet urban hierarchy continues, a slowing in this direction has occurred. Among republics, all had an increasing trend towards largeness on at least one and usually all three summary measures of urban settlement size structure. The RSFSR [Russia] and Armenia especially consistently evidenced a relatively high degree of largeness, while the former Baltic republics generally revealed a relative smallness."     

The impact of binary-star yields on the spectra of galaxies

One of the complexities in modelling integrated spectra of stellar populations is the effect of interacting binary stars besides Type Ia supernovae (SNeIa). These include common envelope systems, cataclysmic variables, novae, and are usually ignored in models predicting the chemistry and spectral absorption line strengths in galaxies. In this paper, predictions of chemical yields from populations of single and binary stars are incorporated into a galactic chemical evolution model to explore the significance of the effects of these other binary yields. Effects on spectral line strengths from different progenitor channels of SNeIa are also explored. Small systematic effects are found when the yields from binaries, other than SNeIa, are included, for a given star formation history. These effects are, at present, within the observational uncertainties on the line strengths. More serious differences can arise in considering different types of SNIa models, their rates and contributions.     

Structural elements in southeastern Quebec,northwestern Appalachians,Canada

An attempt is made to correlate and separate in terms of style and time two contrasting sets of structural elements in the northwestern part of the Appalachian Uplands in the Province of Quebec, Canada. There is sufficient evidence to indicate that a fold system with north-south trending axes is superimposed on a fold system with east-west axes. It is suggested that the two sets of structures represent pulses of one long-continued deformation accompanied by corresponding early and late phases of metamorphism.

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Zusammenfassung Es wurde versucht, in den Appalachen des südöstlichen Teiles der Provinz Quebec, Kanada, zwei ungleichzeitige tektonische Systeme verschiedenen Baustils zu trennen. Die komplexen Kleinstrukturen zeigen, da\ Ost-West streichende Faltenachsen von einer jüngeren Nord-Süd-Faltung überprägt worden sind. Der Autor ist der Meinung, da\ die zwei tektonischen Systeme, die von einer frühen und späten Phase der Metamorphose begleitet werden, den zeitlich getrennten Verformungsstadien einer Orogenese entsprechen.

     

Coastal Massachusetts pond development: edaphic,climatic, and sea level impacts since deglaciation

Kettle ponds in the Cape Cod National Seashore in southeastern Massachusetts differ in their evolution due to depth of the original ice block, the clay content of outwash in their drainage basins, and their siting in relation to geomorphic changes caused by sea-level rise, barrier beach formation, and saltmarsh development. Stratigraphic records of microfossil, carbon isotope, and sediment changes also document late-glacial and Holocene climatic changes.The ponds are separated into 3 groups, each of which follow different development scenarios. Group I ponds date from the late-glacial. They formed in clay-rich outwash, have perched aquifers and continuous lake sediment deposition. The earliest pollen and macrofossil assemblages in Group I pond sediments suggest tundra and spruce-willow parklands before 12 000 yr B.P., boreal forest between 12 000 and 10 500 yr B.P., bog/heath initiation and expansion during the Younger Dryas between 11 000 and 10 000 yr B.P., northern conifer forest between 10 500 and 9500 yr B.P., and establishment of the Cape oak and pitch pine barrens vegetation after 9500 yr B.P. Sedimentation rate changes suggest lowered freshwater levels between 9000 and 5000 yr B.P. caused by decreased precipitation on the Atlantic Coastal Plain. Lake sediment deposition began in the middle Holocene in Group II ponds which formed in clay-poor outwash. These ponds date from about 6000-5000 yr B.P. In these ponds sediment deposition began as sea level rose and the freshwater lens intersected the dry basins. The basal radiocarbon dates of these ponds and stable carbon isotope analyses of the pond sediments suggest a sea-level curve for Cape Cod Bay. Holocene topographic changes in upland and the landscape surrounding the ponds is reconstructed for this coastal area.Group III ponds in the late Holocene landscape of the Provincelands dunes originated as interdunal bogs about 1000 yr B.P. and became ponds more recently as water-levels increased. Peat formation in the Provincelands reflects climatic changes evident on both sides of the Atlantic region.This is the 8th in a series of papers published in this special AMQUA issue. These papers were presented at the 1994 meeting of the American Quaternary Association held 19–22 June, 1994, at the University of Minnesota, Minneapolis, Minnesota, USA. Dr Linda C. K. Shane served as guest editor for these papers.