A Simple and Affordable System for Installing Shallow Drive Point Piezometers

This paper describes a drive point system for installing small‐diameter (15 to 25 mm ID) piezometers to depths of several metres in unconsolidated sediments. The system fills the gap between (1) heavy duty drive point systems powered by drilling rig hydraulics or air hammers that are capable of installing large diameter drive points to depths of many tens of metres and (2) manually driven systems that typically install 10 mm ID or smaller tubing to depths of <2 m. Unlike many existing systems, which install piezometers inside an outer casing that is later removed, our system protects the piezometer screen inside the casing and extends it only once the casing is driven to the desired depth. This avoids clogging of the screen during installation and the risk of creating an annulus around the piezometer, which can provide a preferential pathway for water movement. The piezometer has a larger diameter than most manually driven systems, and thus has a higher yield; it also permits use of most commercially available pressure transducers and electrical conductivity sensors. The piezometers have been successfully installed to depths of up to 6 m using an electric hammer. The system overcomes some issues associated with existing systems and provides the advantages of affordability, rapid installation, mechanical assistance and manual portability.     

New species of Spongia (Porifera: Demospongiae: Dictyoceratida) from New Zealand,and a proposed subgeneric structure

This paper is the fifth in a series revising the taxonomy of New Zealand dictyoceratid sponges (phylum Porifera, subclass Ceractinomorpha, order Dictyoceratida). Six new species of the genus Spongia are added to New Zealand's known fauna. The use of subgenera within the genus Spongia is discussed, and two new subgenera are proposed. The genus Hippospongia is revised, and an emended generic diagnosis is proposed.     

The petrogenesis of sodic island arc magmas at Savo volcano,Solomon Islands

Savo, Solomon Islands, is a historically active volcano dominated by sodic, alkaline lavas, and pyroclastic rocks with up to 7.5 wt% Na₂O, and high Sr, arc-like trace element chemistry. The suite is dominated by mugearites (plagioclase–clinopyroxene–magnetite ± amphibole ± olivine) and trachytes (plagioclase–amphibole–magnetite ± biotite). The presence of hydrous minerals (amphibole, biotite) indicates relatively wet magmas. In such melts, plagioclase is relatively unstable relative to iron oxides and ferromagnesian silicates; it is the latter minerals (particularly hornblende) that dominate cumulate nodules at Savo and drive the chemical differentiation of the suite, with a limited role for plagioclase. This is potentially occurring in a crustal “hot zone”, with major chemical differentiation occurring at depth. Batches of magma ascend periodically, where they are subject to decompression, water saturation and further cooling, resulting in closed-system crystallisation of plagioclase, and ultimately the production of sodic, crystal and feldspar-rich, high-Sr rocks. The sodic and hydrous nature of the parental magmas is interpreted to be the result of partial melting of metasomatised mantle, but radiogenic isotope data (Pb, Sr, Nd) cannot uniquely identify the source of the metasomatic agent.     

Superposed lateral ramps in the Pell City thrust sheet, Appalachian thrust belt, Alabama

In the Appalachian thrust belt in Alabama, thrust sheets of Paleozoic strata generally strike northeastward and are imbricated northwestward; four transverse zones cross the regional strike of the thrust belt. The large-scale Pell City thrust sheet ends southwestward at an oblique lateral ramp within the Harpersville transverse zone, where the leading edge of the thrust sheet (the Pell City fault) curves abruptly 55° counterclockwise. The northwest-striking segment of the Pell City fault conforms to the geometry of an oblique lateral ramp in the footwall. Furthermore, the Pell City fault cuts up section in the hanging wall southwestward toward the transverse zone, indicating a hanging-wall lateral ramp emplaced over the footwall oblique lateral ramp.In the hanging wall adjacent to the northwest-trending segment of the Pell City fault, a pervasive train of upright, isoclinal folds (with 50% apparent shortening) trends N15°W, oblique to the regional translation direction. The fold train is limited to the southwestern part of the Pell City thrust sheet; farther northeast, the regional northeasterly strike prevails. The isoclinal folds in the hanging wall indicate contractional crowding perpendicular to the footwall oblique lateral ramp.     

China's Urbanization in 1949–2015: Processes and Driving Forces

The pace and scale of China's contemporary urbanization are stunning. This paper reviews process and the underlying driving forces of China's urbanization between 1949–2015. Contemporary China's urbanization has experienced four stages, and each has had different driving forces: 1) economic re-construction and industrialization-led urbanization(1949–1977); 2) economic reform and market-led urbanization(1978–1995); 3) economic globalization and the global-local urbanization(1996–2010); and 4) the land-economyled urbanization(2010–). These urbanization processes and driving forces will undoubtedly provide scientific reference and have significant implications for developing countries, especially African countries, to formulate their urbanization public policies.     

Cyclic characteristics of sediments in the Moon Island Beach Subgroup, Newcastle Coal Measures, New South Wales

Cyclic characteristics of a sequence of Permian coal-measure sediments have been studied using Markov chain analysis on borehole data. Fining-upwards and oscillating sequences can be distinguished, and depositional regimes are proposed to explain the observed sequences. However, there is no clearly defined relationship of sequence type to tectonosedimentary environment. The relationship of the number of coal-defined and fining-upwards cycles to total thickness and mean cycle thickness is examined using linear regression. The relationships for coal-defined and fining-upwards cycles are essentially the same. Significant positive correlations are present between the number of cycles and total thickness and significant inverse relationships are present for the number of cycles and the mean cycle thickness.     

The Argo Abyssal Plain

Eighteen geophysical transects were made in the Argo Abyssal Plain to study the magnetic anomalies, bathymetry and seismic structure. Magnetic anomalies were identified as being the Mesozoic anomalies M-10 to M-25, increasing in age from the Java Trench to the northwest continental shelf of Australia. A new bathymetric map shows that the Argo Abyssal Plain is bounded by the 5600-m contour and reaches a maximum depth of 5730 m against the inshore side of the Exmouth Plateau. Joey Rise was found to limit the Argo Abyssal Plain on the southwest. Continuous seismic profiles, sonobuoy data and seismic data from other cruises permit one to contour the depths to oceanic basement. Numerous diapir-like structures were observed, but their nature and origin is obscure.     

The abundance of estuarine larval and juvenile fish in a South Carolina intertidal creek

The fall and winter population of larval fish in a small intertidal creek was measured. The creek was blocked at high tide, and the immature fish were captured in a channel net designed for consistent quantitative sampling as they left with the ebbing tide. A total of 573,739 individuals with a biomass (preserved wet weight) of 66.1 kg were captured during the eight month sampling period (October 1974–May 1975). Twelve families, 13 genera, and 16 species were represented, with five species comprising 99.3% of the fish captured. The five species were:Leiostomus xanthurus (53.5%),Lagodon rhomboides (31.7%),Brevoortia tyrannus (11.9%),Micropogon undulatus (1.7%), andMyrophis punctatus (0.5%). The net was efficient, the catch was seasonal, and the greatest larval abundance occurred in February and March.     

Use of solid-state 13C NMR in structural studies of humic acids and humin from Holocene sediments

¹³C NMR spectra of solid humic substances in Holocene sediments have been obtained using cross polarization with magic-angle sample spinning techniques. The results demonstrate that this technique holds great promise for structural characterizations of complex macromolecular substances such as humin and humic acids. Quantifiable distinctions can be made between structural features of aquatic and terrestrial humic substances. The aliphatic carbons of the humic substances are dominant components suggestive of input from lipid-like materials. An interesting resemblance is also noted between terrestrial humic acid and humin spectra.     

Biogeochemistry and bacteriology of ferrous iron oxidation in geothermal habitats

A survey of hot, acid springs in Yellowstone Park has shown that high concentrations of ferrous and ferric iron are often present. Total ionic iron concentrations in different springs ranged from less than 1 ppm to greater than 200 ppm, and up to 50% of the ionic iron was in the ferrous form. Some of these springs also have high concentrations of reduced sulfur species (S^2? and S⁰). Significant populations of the bacterium Sulfolobus, acidocaldarius, an autotrophic organism able to live and oxidize sulfur compounds at low pH and high temperature, were present in most of these springs. The role of this organism in the oxidation of ferrous iron was investigated by incubating natural samples of water and assaying for disappearance of ferrous iron. Controls in which bacterial activity was inhibited by addition of 10% NaCl were also run. Bacterial oxidation of ferrous iron occurred in most but not all of the spring waters. The temperature optimum for oxidation varied from spring to spring, but significant oxidation occurred at temperatures of 80–85°C, but not at 90°C. Thus, 85–90°C is the upper temperature at which bacterial iron oxidation occurs; a similar upper limit has previously been reported for sulfur oxidation in the same kinds of springs. The steady-state concentrations of ferrous and ferric iron are determined by the rate at which these ions move into the spring pools with the ground water (flow rate), by the rate at which ferric iron is reduced to the ferrous state by sulfide, and by the rate of bacterial oxidation. The bacterial oxidation rate is faster than the flow rate, so that the rate of reduction of ferric iron is probably the rate-controlling reaction. In several springs, no decrease in ferrous iron occurred, even though high bacterial populations were present. It was shown that in these springs, ferrous iron oxidation occurred but the ferric iron formed was reduced back to the ferrous state again. These springs were all high in suspended sediment and the reductant was shown to be present in the sediment. X-ray diffraction revealed that the sediment contained three major ingredients, elemental sulfur, natroalunite, and quartz. Chemical analyses showed a small amount of sulfide, too little to reduce the ferric iron. Elemental sulfur itself did not reduce ferric iron but when elemental sulfur was removed from the sediment by CS₂ extraction, the activity of the sediment was abolished. It is hypothesized that the sulfide present in the sediment (possibly bound to natroalunite) reacts with elemental sulfur to form a reductant for ferric iron. The results show that bacteria can have a profound influence on the ferrous/ferric ratios of geothermal systems, but that temperature and mineral composition of the water may significantly influence the overall result.