Honvang serpentinite body of the Song Ma fault zone, Northern Vietnam: A remnant of oceanic lithosphere within the Indochina–South China suture

The Honvang serpentinite body in the Song Ma fault zone consists mainly of massive serpentinite, altered gabbro and rare chromitite. The serpentinite preserves relict chromian spinel with rare olivine inclusions. The compositional relationship between the Fo content of olivine (Fo_90–92) and Y_Cr [atomic ratio Cr / (Cr + Al) = 0.43–0.44] of chromian spinel suggests that the original peridotite was spinel-bearing lherzolitic harzburgite. Chromitite is typically a high-Al type, consisting of chromian spinel with Y_Cr = 0.43–0.44. Saussuritized fine-grained gabbros display nearly flat rare earth element patterns, suggesting MORB-like affinity. Considering this petrotectonic information, we suggest that the serpentinite body of the Song Ma fault zone represents a remnant of paleo-oceanic lithosphere between the Indochina and South China blocks. The lherzolitic harzburgite may have formed in an environment with low degrees of melt depletion in a slow-spreading setting similar to some Tethyan paleo-oceanic lithospheres.     

Sur les solutions périodiques du mouvement plan de libration des satellites et des planètes

Résumé Ce papier présente une étude analytique du mouvement plan de rotation des satellites (et des planètes) dans leurs mouvements orbitaux. Les trois familles des solution périodiques sont obtenues par la méthode du prolongement analytique de Poincaré. Ensuite, la stabilité de ces solutions périodiques est discutée, et les équations approchées des courbes limites de stabilité sont données jusqu'au quatrième ordre.

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This paper presents an analytical study of the rotational motion of the satellites (and the planets) in their orbital planes. The three families of periodic solutions are obtained by the method of analytical continuation as formulated by Poincaré. The stability of these solutions are analyzed, and the approximate equations of the transition curves are obtained to the fourth order.

     

Effects of fungal infection on lipid extract composition of higher plant remains: comparison of shoots of a Cenomanian conifer, uninfected and infected by extinct fungi

The lipid fraction extracted from uninfected shoots of a fossil conifer, Frenelopsis alata, was analysed by gas-chromatography–mass-spectrometry, and compared with shoots of the same conifer infected by extinct epiphyllous fungi, so as to study the effects of fungal infection on the chemical composition of extracts from higher plant remains. The extracts from the uninfected shoots appeared to be composed of (i) common constituents of higher plant lipids such as n-alkanes and fatty acids, (ii) elemental sulphur, and (iii) substantial amounts of terpenoids characteristic of conifers, such as cadalene, beyerane, dehydroabietane and related compounds. Comparison of this extract with that of fungal-infected shoots revealed, in addition to the aforementioned compounds, the presence of substantial amounts of hydroxysuccinic acid and functionalised benzoic compounds that were interpreted as degradation products of lignin by fungi. This study afforded preliminary indications of the composition of extracts from higher plant remains infected by fungi.     

Global and local sensitivity analyses for coupled thermo–hydro–mechanical problems

This paper focuses on the sensitivity analysis for coupled thermo–hydro–mechanical problems employing both local and global sensitivity methods. A derivative‐based method is used in the local sensitivity approach, whereas the random balance designs method is used for the global sensitivity analysis. The main goal is to investigate the effect of uncertainties in the constitutive parameters on the results from nonlinear coupled thermo–hydro–mechanical analyses of unsaturated soil behavior whose modeling generally involves large sets of constitutive relations. Knowing the parameter sensitivity allows to qualitatively assess the validity of the results obtained by computational simulations of high‐risk situations, for example, emerging nuclear waste repositories. Copyright © 2016 John Wiley & Sons, Ltd.     

Remote sensing mapping of the regeneration of coastal natural habitats in Singapore: Implications for marine conservation in tropical cities

Rapid urbanization has resulted in the loss of coastal and marine habitats in cities worldwide. The effective conservation of urban coastal ecosystems requires detailed knowledge of their spatial distribution, necessitating high-resolution mapping. Our study produces a high-resolution coastal and marine habitat map and shoreline map for the tropical city-state of Singapore created through pixel-based supervised classification of satellite imagery, bathymetry data and expert ground knowledge. These maps can be used as a base reference for multiple applications including ecological research, conservation and urban planning. They also help identifiy trends in the extent of key coastal habitats, providing insight into their differing levels of vulnerability to loss and potential for restoration to ensure long-term resilience. The method used for mapping shoreline typologies and resulting insights gained, can guide other rapidly urbanizing coastal cities on strategies to assemble useful spatial knowledge for effective conservation of their urban coastal ecosystems.     

Downscaling over Vietnam using the stretched-grid CCAM: verification of the mean and interannual variability of rainfall

Rainfall over Vietnam is highly variable from north to south, due to the interaction of the monsoonal winds with the terrain. There is high rainfall from April to September, and little rainfall from October to March (except along the central Vietnam coast). In order to study the ability of the Commonwealth Scientific and Industrial Research Organisation stretched-grid Conformal Cubic Atmospheric Model (CCAM) to capture the climatic and interannual variability of rainfall, downscaled simulations at approximately 20 km horizontal resolution over the region were produced for the period 1979–2001. A scale-selective digital filter was used to force the winds, temperature and sea-level pressure from the ERA-Interim reanalysis for length scales greater than about 700 km. For wind and temperature, the forcing is applied for pressure-sigma levels above about 0.9. ERA-Interim sea surface temperatures were used over the oceans. The simulations were primarily validated against the gridded Asian Precipitation Highly Resolved Observational Data Integration Toward Evaluation of the Water Resources rainfall dataset and station observations using standard statistical methods. It was found that CCAM reproduces well the amount and spatial variability of rainfall, with an area-averaged bias for the entire study domain of less than 1 mm day^?1; CCAM is also able to capture the rainfall pattern under different El Niño Southern Oscillation phases reasonably well for the dry season. For interannual variability, the simulation generally performed better for North and Central Vietnam than for South Vietnam, where rainfall variability was overestimated.     

Broodstock conditioning of New Zealand geoduck (Panopea zelandica) within different temperature and feeding ration regimes

Two-year-old New Zealand geoducks (Panopea zelandica) were conditioned within combinations of three water temperatures (7–8, 11–12 and 16–17 °C) and three feeding rations (10,000, 50,000 and 100,000 cells mL^?1 of Chaetoceros mulleri and Isochrysis galbana) for 73 days. Similar percent matured and dry condition index values were observed among temperatures. However, significantly higher dry gonadosomatic indices (GSI_dw) were recorded at 8 and 12 °C. Although no difference was detected in percentage of spawned individuals and connective tissue occupation indices, a higher percent matured were recorded when fed 10,000 and 50,000 cells mL^?1. A reference group conditioned in pond water became matured 2 months later than the other nine experimental groups, but GSI_dw were similar. To maximise reproductive output, we suggest that 2-year-old P. zelandica may be conditioned in pond water for a month and then in 8 or 12 °C seawater with 50,000 cells mL^?1.     

Transformation of Fish Corrals in Nha Phu Lagoon,Vietnam: livelihood changes and implications

ABSTRACT

Coastal fisheries in Nha Phu lagoon, Vietnam, have encountered dramatic transformation in recent decades. Socio-economic and environmental impacts are examined through the case of fish corrals. The intensification and expansion of fish corrals has helped some households to enhance their income and livelihood assets. Technological and access-related changes associated with this transformation have also resulted in lower incomes, and even pushed poorer households into indebtedness by undermining their livelihood assets. The privatisation of common pool resources has also led to marginalisation of the poor, increasing inequality in access to natural resources and social differentiation, as not all households are able to benefit from the technological changes taking place, while access to natural resources is increasingly concentrated among the wealthier households who are driving this process. A range of measures are needed to alleviate poverty and promote more diverse sustainable livelihood development in fishing communities around the lagoon.     

Assessing the contribution of electrical resistivity tomography (ERT) and self-potential (SP) methods for a water well drilling program in fractured/karstified limestones

ERT and SP investigations were conducted in carbonate rocks of the Dinant Synclinorium (Walloon Region of Belgium) to find suitable locations for new water wells in zones with little hydrogeological data. Since boreholes information needed to be representative of the area, large fractured zones were searched for the drillings. Large ERT profiles (320 to 640 m) allowed us to image the resistivity distribution of the first 60 m of the subsurface and to detect and characterize (in terms of direction, width and depth) fractured zones expected to be less resistive. Data errors, depth of investigation (DOI) indexes and sensitivity models were analyzed in order to avoid a misinterpretation of the resulting images. Self-potential measurements were performed along electrical profiles to complement our electrical results. Some negative anomalies possibly related to preferential flow pathways were detected. A drilling campaign was conducted according to geophysical results. ‘Ground truth’ geological data as well as pumping tests information gave us a way to assess the contribution of geophysics to a drilling program. We noticed that all the wells placed in low resistivity zones associated with SP anomalies provide very high yields and inversely, wells drilled in resistive zones or outside SP anomalies are limited in terms of capacity. An apparent coupling coefficient between SP signals and differences in hydraulic heads was also estimated in order to image the water table.