Characterization of sulfate mineral deposits in central Thailand          下载免费PDF全文

Junichiro Kuroda  Hidetoshi Hara  Katsumi Ueno  Thasinee Charoentitirat  Teruyuki Maruoka  Takashi Miyazaki  Akira Miyahigashi  Stefano Lugli 《Island Arc》2017,26(2)

In this paper we present petrographic and geochemical data of sulfate mineral deposits in northeast Nakhon Sawan, central Thailand, and provide new constraints on their age. The deposits are made up mainly of strongly deformed nodular and massive gypsum in the upper part, and less deformed layered anhydrite in the lower part. They are intruded by andesitic dikes that contain Middle Triassic zircons (ca 240 Ma). These dikes are probably part of the regional magmatic activity of the Sukhothai Arc during the Early to Middle Triassic. Sulfur (δ³⁴S) and strontium (⁸⁷Sr/⁸⁶Sr) isotopic compositions of the sulfates range from 15.86 ‰ to 16.26 ‰ and from 0.70810 to 0.70817, respectively. Comparisons with the Phanerozoic seawater isotopic evolution curve indicate that those values are best explained by precipitation of the sulfates from Carboniferous seawater, in particular seawater of late Mississippian age (ca 326 Ma), and this would be consistent with previous studies of calcareous fossils in the limestones that crop out around this site. Our interpretation is that evaporitic gypsum was originally precipitated from hypersaline seawater on a shallow lagoon or shelf on the Khao Khwang Platform during the Serpukhovian, and that this gypsum changed to anhydrite during early burial. The anhydrite was then cut by andesitic dikes during the Middle Triassic, and more recently the upper part of which was rehydrated during exhumation to form secondary gypsum near the surface.  相似文献   

A climate-informed,ecosystem approach to fisheries management     

《Marine Policy》2015

This paper outlines the benefits of using the framework for an ecosystem approach to fisheries management (EAFM) for dealing with the inevitable yet unclear impacts of climate change and ocean acidification on coastal fisheries. With a focus on the Asia-Pacific region, it summarizes the projected biological and socio-economic effects of increased emissions of carbon dioxide (CO₂) for coastal fisheries and illustrates how all the important dimensions of climate change and ocean acidification can be integrated into the steps involved in the EAFM planning process. The activities required to harness the full potential of an EAFM as an adaptation to climate change and ocean acidification are also described, including: provision of the necessary expertise to inform all stakeholders about the risks to fish habitats, fish stocks and catches due to climate change; promotion of trans-disciplinary collaboration; facilitating the participation of all key stakeholders; monitoring the wider fisheries system for climate impacts; and enhancing resources and capacity to implement an EAFM. By channeling some of the resources available to the Asia-Pacific region to adapt to climate change into an EAFM, developing countries will not only build resilience to the ecological and fisheries effects of climate change, they will also help address the habitat degradation and overfishing presently reducing the productivity of coastal fisheries.  相似文献   

Growth of Asia in the Late Triassic Continent-Continent Collision of Shan-Thai and Indochina Against South China     

S. Bunopas  P. Vella  H. Fontaine  S. Hada  C. Burrett  P. Haines  S. Potisat  Th. Wongwanich  P. Chaodamrong  K.T. Howard  S. Khositanont 《Gondwana Research》2001,4(4):584-585

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BVRI CCD-Photometry of Comparison Stars in the Fields of Galaxies with Active Nuclei. VI     

V. T. Doroshenko  Yu. S. Efimov  G. A. Borman  N. G. Pulatova 《Astrophysics》2014,57(1):30-49

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Earthquake hazard of dams along the Mekong mainstream     

Santi Pailoplee 《Natural Hazards》2014,74(3):1813-1827

In this study, the earthquake hazard was evaluated for all of 19 of the proposed or built dams along the Mekong River. All values representing a potential indication of hazardous earthquakes, such as the closest earthquake and seismogenic faults and including the seismic parameters required for a seismic safety evaluation, were clarified. The results will be useful in reviewing the safety of existing dams and for the design of suitable earthquake resistant specifications for any currently or future planned dam construction in this area. Seismotectonically, 14 of the 19 proposed Mekong River dams are located within an earthquake source zone. Most of faults are potentially still active, according to both seismicity and paleoseismological evidence. In addition, the maximum credible earthquakes were estimated to be in the range of 7–8 Mw for the closest fault zone of each dam. Previous isoseismal maps indicated a risk of shaking intensities of around scale III–IV (Modified Mercalli Intensity Scale) for the dams. According to the preliminary ranging of the International Commission on Large Dams, 9 of these 19 dams are classified as in an extreme hazard class and so need careful observation and monitoring of hazardous earthquakes. An effective mitigation plan should also be prepared for each operating dam.  相似文献   

Analysis of fracture propagation in a rock mass surrounding a tunnel under high internal pressure by the element-free Galerkin method     

《Computers and Geotechnics》2014

Fractures developed around high pressurized gas or air storage tunnels can progressively extend to the ground surface, eventually leading to an uplift failure. A tool reasonably reproducing the failure patterns is necessary for stability assessment. In this study, a numerical method based on the element-free Galerkin (EFG) method with a cohesive crack model is developed to simulate fracture propagation patterns in the rock mass around a tunnel under high internal pressure. A series of physical model tests was also conducted to validate the reliability of the developed method. A qualitative agreement between physical model tests and numerical results can be obtained. The in situ stress ratio, k, has a strong influence on both the position of crack initiation and the propagation direction. The numerical analyses were extended to full-scale problems. Numerical tests were performed to investigate the prime influencing factors on the failure patterns of a high pressurized gas circular tunnel with varying parameters. The results suggest that initial in situ stress conditions with a high k (larger than 1) is favorable for construction of pressurized gas or air storage tunnels.  相似文献   

Consolidation behavior of soft deposits considering the variation of prefabricated vertical drain discharge capacity     

《Computers and Geotechnics》2014

This paper is primarily focused on why and how to consider the varied discharge capacity during simulations of consolidation via prefabricated vertical drains (PVDs) for soft soil deposits. First, the existing studies regarding discharge capacity are summarized and discussed. These studies conclude that the discharge capacity of PVDs at sites vary with the confining pressure and consolidation time. Next, a series of analytical solutions that consider the variation of discharge capacity with ground depth, consolidation time or both simultaneously are presented and compared. Applications of these solutions and of the newly introduced parameters are described. Then, a well-documented case history on ground treatment with PVDs is analyzed, in which the parameters related to the time-dependent discharge capacity were obtained from laboratory tests. A comparison between a classical solution and the newly presented method indicates that consideration of the varied discharge capacity in the consolidation theory can better predict the consolidation process of PVD-improved ground.  相似文献   

Lead isotope signatures of Holocene fluvial sediments from the Loire River valley     

《Applied Geochemistry》2004,19(6):957-972

The distribution of Mn, V, Th, Pb and isotopes of Pb in the labile fraction of sediments from a channel infill in the Middle Loire alluvial plain are used to highlight some aspects of the basin evolution over the period from 0 to 10 ka BP. The acid extractable matter (AEM) in the sediment samples is variable in amount and in trace element contents. Iron-Mn oxyhydroxides are the principle trace element carrying phase in the labile fraction and carbonates are a secondary carrier. Vanadium and Pb originate from the weathering of silicates and are used as a silicate erosion rate index in the fluviatile record. Most of the AEM data plot along a general trend between 3 endmembers (basalts, Cretaceous carbonate rocks and granites) in the relationship between ²⁰⁷Pb/²⁰⁶Pb and ²⁰⁶Pb/²⁰⁶Pb. These endmembers have been mixed in various proportions depending on natural Holocene inputs (erosion, volcanic events) or human influences (mining and smelting of ore).  相似文献   

Estimating emissions from forest fires in Thailand using MODIS active fire product and country specific data   总被引：1，自引：0，他引：1  

Agapol Junpen  Savitri Garivait  Sebastien Bonnet 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(3):389-400

Studies on air pollution and climate change have shown that forest fires constitute one of the major sources of atmospheric trace gases and particulate matter, especially during the dry season. However, these emissions remain difficult to quantify due to uncertainty on the extent of burned areas and deficient knowledge on the forest fire behaviours in each country. This study aims to estimate emissions from forest fires in Thailand by using the combination of the Moderate Resolution Imaging Spectroradiometer (MODIS) for active fire products and country-specific data based on prescribed burning experiments. The results indicate that 27817 fire hotspots (FHS) associated with forest fires were detected by the MODIS during 2005–2009. These FHS mainly occurred in the northern, western, and upper north-eastern parts of Thailand. Each year, the most significant fires were observed during January–May, with a peak in March. The majority of forest FHS were detected in the afternoon. According to the prescribed burning experiments, the average area of forest burned per fire event was found to fall within the range 1.09 to 12.47 ha, depending upon the terrain slope and weather conditions. The total burned area was computed at 159309 ha corresponding to the surface biomass fuel of 541515 tons dry matter. The forest fire emissions were computed at 855593 tons of CO₂, 56318 tons of CO, 3682 tons of CH₄, 108 tons of N₂O, 4928 tons of PM_2.5, 4603 tons of PM₁₀, 357 tons of BC and 2816 tons of OC.  相似文献   

Forum discussion: influence of cyclic component on re-scaled range analysis     

《Quaternary International》2003,99(1):101-103

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