Estimating coefficients of volume compressibility from compression of strata and piezometric changes in a multiaquifer system in west Taiwan

This paper estimates the coefficients of volume compressibility from variation in compressible layer thickness and changes in piezometric heads by using detail ground surface surveys and a multilayer monitoring well at a selected site (Shigang) within the Choshui River alluvial fan in west Taiwan. The paper integrates various types of in situ monitoring tools, including leveling surveys, continuous global position system (GPS) stations, multilevel layer compression and groundwater pressure head-monitoring wells, to investigate the situation and progress of the subsidence problem in the region. The results from the cross-analyses of the measured data show that surface settlement caused by the compression of strata is between the depths of 60 and 210 m where the clayey stratum within 120-180 m was most pronounced and contributes up to 53% of the total compression. The results indicate that the clayey stratum is under normal consolidation. The results also reflect the fact that 20% of settlement contribution comes from the sandy stratum within 90-120 m; the elasto-plastic behavior of this sandy stratum is clear. The coefficients of volume compressibility of the clayey and sandy stratum analysed from the stratum's compression records; they were 6.38×10⁻⁸ and 5.71×10⁻⁹ m²/N, respectively. Ultimately, this parameter estimation would permit to control and predict land subsidence based on change in pressure head which are related to groundwater extraction.     

On the long-term seismic hazard analysis in the Zhangjiakou–Penglai seismotectonic zone, China

The Zhangjiakou–Penglai seismotectonic zone (ZPSZ) lies in the northern part of North China and extends along the Zhangjiakou–Beijing–Tianjin–Bohai Bay–Penglai–Yellow Sea. It is about 900 km long and some 250 km wide in a northwest direction. The great Sanhe-Pinggu (M_S=8.0) earthquake occurred on September 1679 and the Tangshan (M_S=7.8) earthquake on July 1976 caused serious economic and life losses. According to some differences in crust structure and regional tectonic stress field, the ZPSZ is divided into western and eastern segment by the 117°E line for study on long-term seismic hazard analysis. An analysis of Gutenberg–Richter's empirical relation of earthquake-frequency and time process of historic and recent earthquakes along the eastern and western segments shows that the earthquake activity obeys a Poisson process, and these calculations indicate that the earthquake occurrence probability of M_S=6.0–6.9 is 0.77–0.83 in the eastern segment and the earthquake occurrence probability of M_S=7.0–7.9 is 0.78–0.80 in the western segment of the ZPSZ during a period from 2005 to 2015.     

High-Ti type N-MORB parentage of basalts from the south Andaman ophiolite suite,India

A complete dismembered sequence of ophiolite is well exposed in the south Andaman region that mainly comprises ultramafic cumulates, serpentinite mafic plutonic and dyke rocks, pillow lava, radiolarian chert, and plagiogranite. Pillow lavas of basaltic composition occupy a major part of the Andaman ophiolite suite (AOS). These basalts are well exposed all along the east coast of southern part of the south AOS. Although these basalts are altered due to low-grade metamorphism and late hydrothermal processes, their igneous textures are still preserved. These basalts are mostly either aphyric or phyric in nature. Aphyric type exhibits intersertal or variolitic textures, whereas phyric variety shows porphyritic or sub-ophitic textures. The content of alkalies and silica classify these basalts as sub-alkaline basalts and alkaline basalts. A few samples show basaltic andesite, trachy-basalt, or basanitic chemical composition. High-field strength element (HFSE) geochemistry suggests that studied basalt samples are probably derived from similar parental magmas. Al₂O₃/TiO₂ and CaO/TiO₂ ratios classify these basalts as high-Ti type basalt. On the basis of these ratios and many discriminant functions and diagrams, it is suggested that the studied basalts, associated with Andaman ophiolite suite, were derived from magma similar to N-MORB and emplaced in the mid-oceanic ridge tectonic setting.     

A brief comparison of lava flows from the Deccan Volcanic Province and the Columbia-Oregon Plateau Flood Basalts: Implications for models of flood basalt emplacement

The nature and style of emplacement of Continental Flood Basalt (CFB) lava flows has been a matter of great interest as well as considerable controversy in the recent past. However, even a cursory review of published literature reveals that the Columbia River Basalt Group (CRBG) and Hawaiian volcanoes provide most of the data relevant to this topic. It is interesting to note, however, that the CRBG lava flows and their palaeotopographic control is atypical of other CFB provinces in the world. In this paper, we first present a short overview of important studies pertaining to the emplacement of flood basalt flows. We then briefly review the morphology of lava flows from the Deccan Volcanic Province (DVP) and the Columbia-Oregon Plateau flood basalts. The review underscores the existence of significant variations in lava flow morphology between different provinces, and even within the same province. It is quite likely that there were more than one way of emplacing the voluminous and extensive CFB lava flows. We argue that the establishment of general models of emplacement must be based on a comprehensive documentation of lava flow morphology from all CFB provinces.     

Minority women’s microenterprises in rural areas of the United States of America: African American,Hispanic American and Native American case studies

Women in many rural areas of the US often engage in small-scale businesses as one of several avenues for contributing to household incomes. In those geographical areas that contain a significant minority population, many of the women's businesses display the cultural diversity of the regions in which they live. Likewise, women's roles as economic providers as well as wives and mothers are reflected in the manner in which they operate their businesses. Candida Brush suggests that women's strategies for operating their businesses are highly integrative because women's business decisions are intertwined with familial responsibilities, household economic demands and desires to contribute to their communities. Hispanic and Native American women in the Four Corners region of southwestern US and African American women in central Virginia participated in interviews in which they responded to numerous short answer and open-ended questions about their businesses and decision-making strategies. From these interviews an image emerges of rural minority business women who are operating their businesses at the nexus of family obligations, economic necessities, cultural ties and with a commitment for serving their communities. This revised version was published online in July 2006 with corrections to the Cover Date.     

Improving Sequential Simulation with a Structured Path Guided by Information Content

Multiple-point simulation is a newly developed geostatistical method that aims at combining the strengths of two mainstream geostatistical methods: object-based and pixel-based methods. It maintains the flexibility of pixel-based algorithms in data conditioning, while enhancing its capability of reproducing realistic geological shapes, which is traditionally reserved to object-based algorithms. However, the current snesim program for multiple-point simulation has difficulty in reproducing large-scale structures, which have a significant impact on the flow response. To address this problem, we propose to simulate along a structured path based on an information content measure. This structured path accounts for not only the information from the data, but also some prior structural information provided by geological knowledge. Various case studies show a better reproduction of large-scale structures. This concept of simulating along a structured path guided by information content can be applied to any sequential simulation algorithms, including traditional variogram-based two-point geostatistical algorithms.     

Simulations of a coupled hydro-chemo-mechanical system in rocks

A coupled hydro-chemo-mechanical numerical model is developed for these coupled phenomena in many engineering fields. The model has been applied to predicting the response of a stressed rockmass column to an injected reactive fluid (reagent) flow. The response includes evolutions of porosity, permeability, reagent and mineral concentrations during dissolution. In the model, the progress of dissolution is defined by the change in porosity ratio and the porosity increases with dissolution assuming there is no precipitation. The numerical evolutions of porosity, permeability, reagent and mineral concentrations during dissolution are validated against steady state solutions. The model results show that these evolutions are regulated to a certain extent by the applied external loadings: an applied extensional stress enhances the progress of the dissolution process while an applied compression stress slows the progress of the dissolution process. This revised version was published online in July 2006 with corrections to the Cover Date.     

The influence of hydrocarbon expulsion on carbon isotopic compositions of individual n-alkanes in pyrolysates of selected terrestrial kerogens

Expulsion of petroleum from source rock is a complex part of the entire migration process. There exist fractional effects on chemical compositions in hydrocarbon expulsion. Does the carbon isotopic fractionation occur during expulsion and to what extent? Here the influence of hydrocarbon expulsion on carbon isotopic compositions of individual n-alkanes from pyrolysates of selected terrestrial kerogens from Tuha basin and Fushun, Liaoning Province of China has been experimentally studied. The pyrogeneration-expulsion experiments were carried out under semi-closed system. The carbon isotopic compositions of individual n-alkanes were measured by GC-IRMS. The main conclusions are as follows. First, there is carbon isotopic fractionation associated with hydrocarbon expulsion from Type III kerogens in Tuha Basin. There exist differences of carbon isotopic compositions between the unexpelled n-alkanes and expelled n-alkanes from Tuha desmocollinite and Tuha mudstone. Second, there is almost no carbon isotopic fractionation associated with hydrocarbon expulsion from Type II kerogens in Fushun and Liaohe Basin. Third, carbon isotopic fractionation in hydrocarbon expulsion should be considered in making oil-source correlation of Type III kerogens at least in the Tuha Basin. Further studies need to be carried out to determine whether this is true in other basins. Fourth, oil and source at different maturity levels cannot be correlated directly for Type III kerogens since the carbon isotopic compositions of expelled hydrocarbons at different temperatures are different. The expelled hydrocarbons are usually lighter (depleted in ¹³C) than the hydrocarbons remaining in the source rock at the same maturity.     

Pollution history and recovery of a boreal lake exposed to a heavy bleached pulping effluent load

We examined the effects of heavy pulp mill discharges on the Lake Lievestuoreenjärvi ecosystem and the later recovery of diatom and chironomid communities from age-dated short core samples. Beginning in 1927 the lake received a heavy effluent load from a sulphite pulp mill. Except for the recession during the Second World War and the temporary closure of the mill from 1967 to 1971, the industrial load, containing large quantities of nutrients, organic matter and toxic compounds, increased continuously. In the early 1980s, laboratory documents were falsified by the directors of the mill and the systematic illegal effluent overload led to a collapse of the whole lake ecosystem. In 1985, the outdated plant was finally closed down. Based on the assessment of chemical properties and biological remains of the sediment, we distinguished five developmental phases in the ecological state of the lake. In the pre-industrial phase, the pelagic and profundal benthic communities were dominated by species preferring ultraoligotrophic or oligotrophic lakes. Concomitant with the increasing discharge and deposition of chlorine compounds, resin acids, and mercury, as well as strong acidity and hypolimnetic and epilimnetic anoxia, the ecological status changed in a short period from excellent to bad. Finally, in the early 1960s, the majority of the lake was virtually dead and the aquatic life survived only in the uppermost littoral zone. Since 1985, a fast recovery in the water quality has led to a strong, but temporary eutrophy in pelagic communities. The main peak of eutrophication was caused by the invasion of a species new to the lake,Aulacoseira granulata var.angustissima. Later, the pelagic communities shifted towards oligotrophy, but the original, pre-industrial status has not been re-established. The profundal benthic communities have not achieved the pre-industrial structure, but at present indicate mesotrophy.