辽宁凌源四合当地区九佛堂组珍稀化石层划分及意义

辽宁省凌源市四合当地区九佛堂组含有丰富的中生代热河生物群化石,尤其是珍稀化石.通过剖面测制、化石采集以及实地调查等手段,将九佛堂组划分为3个段,确定了化石层的分布及重要化石的产出层位,同时命名了3个化石层：一段的韩家沟层、二段的卅二道湾层、三段的四合当层,加深了辽西九佛堂组化石层的研究程度.     

Transport behavior of nZnO in geosynthetic clay liner used in municipal solid waste landfills under temperature effect

The transport process of nZnO in geosynthetic clay liner (GCL), an anti-seepage material used in municipal solid waste (MSW) landfills, under different seepage temperature conditions was conducted. The transport behavior of nZnO in GCL was analyzed. Results showed that the retardation performance of current GCL used in MSW landfills anti-seepage system against nZnO pollutants was poor. nZnO successfully permeated the GCL and entered external soil–groundwater environment, posing health threats to the life of organisms. Although seepage temperature exerted a small effect on nZnO suspension leakage volume, change in seepage temperature affects the mass of transported nZnO in GCL by redispersion of nZnO in suspension. As the seepage temperature increases, the mass of nZnO that permeated the GCL increases, reaching a maximum at 50 °C, and then decreases.     

Evolution of the shape parameter in the Weibull distribution for brittle rocks under uniaxial compression

Applying the statistical damage theory based on the Weibull distribution to describe rock deformation and failure processes is an important development in rock mechanics. The shape parameter of the Weibull distribution, m, determines the basic shape of the distribution curve; additionally, it also represents a physical characteristic which can be applied when constructing rock constitutive models. To study the evolution of m during rock failure when applying the Weibull distribution to rock mechanics, uniaxial cyclic loading tests of shale specimens were conducted and previous rock mechanics experiments under different temperatures and loading rates were reviewed. The results indicate that m varied with the accumulation of damage but was almost constant between the volume expansion point and the peak strength point of each specimen. Combined with previous studies about the accelerated failure behavior of rocks, we conclude that between the volume expansion point and the peak strength point, the mechanical behavior of the rock fracture process did not change significantly. Based on the characteristics of m at different damage stages during the rock failure process, ranges of m values at different damage stages are proposed. The conclusions reached in this study may be used as an important reference for theoretical research on rock mechanics.     

基于GF-2影像西藏桑耶地区岩性-构造遥感解译

西藏桑耶地区位于青藏高原中南部,区内切割强烈,地势陡峻,属于高山峡谷区。为提高区域地质调查野外工作效率,在调查中率先开展了遥感解译研究。在充分收集已有资料的基础上,通过对GF-2卫星数据进行预处理和影像增强,结合野外验证建立了各地质要素的遥感解译标志,实现了区内不同地层岩性、侵入岩、断裂和褶皱等地质要素的提取,最终编制了研究区1:5万遥感地质解译图,为区域地质调查提供了数据支撑。结果表明: 各地质要素在GF-2数据上均有良好反映,完全满足1:5万尺度的遥感地质解译和编图的需要,充分显示出该卫星数据在区域地质调查等工作中具有良好的应用前景。     

A preliminary study on the spatial distribution characteristics and causes of strontium-rich mineral water in the Dushan complex

The mountain rocks in the Dushan Complex are Sr-rich granite with a much higher Sr level than those in other crustal lithospheres in eastern China. That presents a high potential for developing Sr-rich mineral water. In this study, 6 groups of rock samples, together with 30 groups of water samples, were collected. Combining with the existing data, the Sr contents in three different types of underground water were obtained, which are the Quaternary pore water, the meshed bedrock fissure water in weathered zones and the tectonic bedrock fissure water. On the basis of preliminary understanding for the distribution characteristics of Sr-rich mineral water in the Dushan Mountain region, the causes for the Sr-rich mineral water were investigated. Our results showed that the Sr content of the rocks in the studied area ranges from 988 to 1 950 μg/g. In the horizontal direction, those in both the pore water and the meshed bedrock fissure water in weathered zones show high values in the west but low ones in the east, and high ones in the south but low ones in the north. Furthermore, both types of water meet the standard for Sr-rich mineral water in the western areas. In the vertical direction, the Sr content shows the lowest value in pore water(the average value is 0.707 mg/L), middle value in the meshed bedrock fissure water in weathered zones(the average value is 1.415 mg/L) and the highest value in the tectonic bedrock fissure water(the average value is 8.331 mg/L). It was thought that the widely-developed Sr-rich granite in this region provides physical sources for the formation of Sr-rich mineral water. The continuous dissolution of Sr during underground water runoff is the internal mechanism. In addition, the hydraulic interrelations may exist between the three vertical aquifers, leading a continuous accumulation of the Sr level during infiltration.     

Porosity and wave velocity evolution of granite after high-temperature treatment: a review

The evolution of porosity and changes in wave velocity in granite after high-temperature treatment has been experimentally investigated in different studies. Statistical analysis of the test results shows that there is a temperature threshold value that leads to variations in porosity and wave velocity. At a temperature that is less than 200 °C, the porosity of granite slowly increases with increases in temperature, while the wave velocity decreases. When the temperature is greater than 200 °C (especially between 400 and 600 °C), the porosity quickly increases, while the wave velocity substantially decreases. The temperature ranges of room temperature to 200 and 200–400 °C correspond to the undamaged state and the micro-damage state, respectively. The results confirm that there is an important link between the variations of physical and mechanical properties in response to thermal treatment. By studying the relationships among rock porosity, wave velocity and temperature, this provides the basis for solving multi-variable coupling problems under high temperatures for the thermal exploitation of petroleum and safe disposal of nuclear waste.     

Reservoir architecture and fracture characterization of low-permeability sandstone reservoir: a case study of Biandong oilfield,Jinhu depression,northern Jiangsu Basin,China

Fracture is one of the most important factors through the whole process of low-permeability reservoir development. Biandong oilfield is a typical low-permeability fractured sandstone reservoir, and has stepped into high water cut stage; thus, the waterflooding effect is poor. Therefore, many contradictions such as high moisture content, decreasing production speed, and low recovery efficiency are becoming increasingly prominent, which have seriously hindered the sustainable development, and need to be solved urgently. However, few such studies on reservoir characterization in low-permeability fractured sandstone reservoir have been conducted in China. In this study, through comprehensive analysis on reservoir characterization and sedimentary environment, significant results are achieved. Three types of fracture occurrence are identified; they are high-angle fracture, low-angle fracture, and horizontal fracture, respectively. Two types of reservoir pore (primary porosity and secondary porosity) are recognized based on thin-section observation and analysis. The diagenetic stage of Biandong oilfield are divided into three stages, early A, early B, and late A, respectively. Finally, a regional discrete fracture network model is established with Fisher’s algorithm based on three-dimensional geological model. All the research results presented above can make a significant instructing function for making reservoir development plan and improving recovery efficiency.     

Mechanical behavior and micro-structure of cement kiln dust-stabilized expensive soil

In this study, the effects of cement kiln dust (CKD) on the swelling properties, strength properties, and microstructures of CKD-stabilized expansive soil were investigated. Samples were prepared and stabilized with different CKD content ratios, ranging from 0 to 18% by dry mass. The results obtained show that the maximum swelling pressures decrease exponentially with increases in CKD content. Both the cohesion and unconfined compressive strength (UCS) increase at ratios below 10% CKD and then decrease slightly, above that ratio. CKD can also improve the strength of saturated, expansive soil. There is no visible change of UCS for soil without CKD when cured, while the UCS of a sample with 10% CKD content after curing for 90 days is higher than that after curing for only 1 day. This indicates that CKD can improve the long-term strength of expansive soil. Finally, microstructure analysis reveals that the addition of CKD reduces the montmorillonite content of expansive soil and decreases its swelling properties. The addition of CKD also changes the pore volume distribution, both the size and amount of macro-pores and micro-pores decrease with increase in CKD content. For saturated samples, the size of macro-pores is obviously reduced, while that of micro-pores is slightly increased for both treated and untreated soils. Hydration and saturation processes make the soil structure become dispersive which results in a lower strength, and adding CKD can restrain this process. The suggested optimal CKD content is between 10 and 14% and with a curing time of more than 27 days.     

A GIS-based method of risk assessment on no. 11 coal-floor water inrush from Ordovician limestone in Hancheng mining area,China

The no. 11 coal seam in the deep area of Hancheng mining area is mining in recent years, which is threatened by the water inrush from the Ordovician limestone aquifer. Coal-floor water inrush is governed by the water abundance of coal-floor aquifer, the water-resisting performance of coal-floor aquitard, and the pathway connecting the water source and the working face. To make an accuracy risk assessment of water inrush from the no. 11 coal seam floor, a GIS-based vulnerability index method (VIM) is adopted for its superior comprehensive consideration of more controlling factors, powerful spatial analysis, and intuitively display functions. This study firstly established an index system including the water pressure of the coal-floor aquifer, the unit water inflow, the thickness, the core recovery percentage, the thickness ratio of brittle rocks to ductile rocks, the thickness of effective aquitard, and the accumulated length of faults and folds, of which the former six indexes governed the water abundance of the coal-floor aquifer which was combined with the last two factors to determine the risk of coal-floor water inrush. Secondly, the thematic map of each controlling factor is established by GIS using the geological prospecting data, and the weight of each factor is determined by the analytic hierarchy process (AHP) after consulting the expert review panel. At last, a vulnerability index is obtained and used to assess the risk of coal-floor water inrush of the no. 11 coal seam. The risk of water inrush of the no. 11 coal seam of the study area was ranked to three zones: the southeastern shallow area in red color is the dangerous zone, the wide northwestern area in green color is the safe zone, and the transition area in yellow color is the moderate-risk zone. Compared with the actual water-inrush incidents, the risk assessment result was verified to achieve an accuracy of 82.35%, which is proved to be a dependable reference for the prevention and controlling of coal-floor water inrush of the no. 11 coal seam in Hancheng mining area.     

皖南东至兆吉口铅锌矿床成矿时代的厘定及其找矿指示意义

皖南东至兆吉口铅锌矿床是近年来在江南过渡带西段新发现的一个规模达中型的中-低温热液型矿床。目前揭露的铅锌矿体均赋存于东至断裂带及其西侧次级张(扭)性断裂及裂隙中。文章选取了该矿床主要矿石矿物闪锌矿以及与主成矿阶段金属硫化物紧密共生的石英,分别采用流体包裹体Rb-Sr法和40Ar-39Ar法进行同位素地质年龄测定。4件闪锌矿样品获得流体包裹体Rb-Sr等时线年龄为(128±1)Ma;2件石英样品获得流体包裹体40Ar-39Ar坪年龄分别为(128.74±3.02)Ma和(128.19±1.98)Ma,等时线年龄分别为(128.81±5.25)Ma和(128.30±3.47)Ma,反等时线年龄分别为(128.82±5.24)Ma和(128.31±3.47)Ma。同位素地质年龄测试结果基本一致,表明兆吉口铅锌矿床形成于128 Ma左右,成矿时代为早白垩世。该成矿年龄与赋矿闪长玢岩的形成时间((129.0±2.3)Ma~(128.4±2.7)Ma)一致,也与东至断裂燕山晚期的活动年龄((126.3±2.2)Ma)相近,表明该矿床成矿与燕山晚期的构造-岩浆活动密切相关,此时区域构造背景为强烈挤压后的伸展环境。这一矿化事件在成矿时代上明显晚于长江中下游成矿带中的断隆区(如铜陵、安庆-贵池等矿集区)的铜金多金属矿床和皖南成矿带中的钨钼多金属矿床(136 Ma),而与长江中下游成矿带断坳区的玢岩铁矿床的成矿时间(135~127 Ma)相近,指示长江中下游成矿带与皖南成矿带之间的江南过渡带中发育有燕山晚期较晚阶段(128 Ma左右)的铅锌矿化事件,为今后在该区开展铅锌多金属矿床找矿勘探提供了重要依据。