Analysis of hydrogeolgical characteristics and water environmental impact pathway of typical shale gas exploration and development zones in Sichuan Basin,China

Studying the influence of shale gas exploration and development on groundwater environment is the basis of guiding water environment protection in the process of shale gas exploration and development. Groundwater environmental pollution is concealed, complex and persistent. Once it is difficult to control the pollution, the current commercial shale gas development zones in Sichuan Basin that are mostly located in karst areas and highly sensitive to groundwater will be vulnerable to the impact of shale gas exploration and development. Based on the hydrogeological conditions of shale gas exploration and development area and combined with engineering analysis of exploration and development, various risk pathways that may affect the groundwater environment during process of shale gas exploration, mining well construction, mining operations and other stages were identified in this paper. Some existing risk pathways were proved by verification of typical areas and should not be ignored. Based on the actual situation of typical areas, the countermeasures of groundwater environmental protection in the process of shale gas exploration and development in karst areas were discussed. It is believed that the ground-water environment can be better protected by strengthening administration, research and application of new technologies, precise design, hydrogeological conditions, and research and feedback of groundwater environmental protection.     

Paragenesis and geochemistry of ore minerals in the epizonal gold deposits of the Yangshan gold belt,West Qinling,China

Six epizonal gold deposits in the 30-km-long Yangshan gold belt, Gansu Province are estimated to contain more than 300 t of gold at an average grade of 4.76 g/t and thus define one of China's largest gold resources. Detailed paragenetic studies have recognized five stages of sulfide mineral precipitation in the deposits of the belt. Syngenetic/diagenetic pyrite (Py₀) has a framboidal or colloform texture and is disseminated in the metasedimentary host rocks. Early hydrothermal pyrite (Py₁) in quartz veins is disseminated in metasedimentary rocks and dikes and also occurs as semi-massive pyrite aggregates or bedding-parallel pyrite bands in phyllite. The main ore stage pyrite (Py₂) commonly overgrows Py₁ and is typically associated with main ore stage arsenopyrite (Apy₂). Late ore stage pyrite (Py₃), arsenopyrite (Apy₃), and stibnite occur in quartz ± calcite veins or are disseminated in country rocks. Post-ore stage pyrite (Py₄) occurs in quartz ± calcite veins that cut all earlier formed mineralization. Electron probe microanalyses and laser ablation-inductively coupled plasma mass spectrometry analyses reveal that different generations of sulfides have characteristic of major and trace element patterns, which can be used as a proxy for the distinct hydrothermal events. Syngenetic/diagenetic pyrite has high concentrations of As, Au, Bi, Co, Cu, Mn, Ni, Pb, Sb, and Zn. The Py₀ also retains a sedimentary Co/Ni ratio, which is distinct from hydrothermal ore-related pyrite. Early hydrothermal Py₁ has high contents of Ag, As, Au, Bi, Cu, Fe, Sb, and V, and it reflects elevated levels of these elements in the earliest mineralizing metamorphic fluids. The main ore stage Py₂ has a very high content of As (median value of 2.96 wt%) and Au (median value of 47.5 ppm) and slightly elevated Cu, but relatively low values for other trace elements. Arsenic in the main ore stage Py₂ occurs in solid solution. Late ore stage Py₃, formed coevally with stibnite, contains relatively high As (median value of 1.44 wt%), Au, Fe, Mn, Mo, Sb, and Zn and low Bi, Co, Ni, and Pb. The main ore stage Apy₂, compared to late ore stage arsenopyrite, is relatively enriched in As, whereas the later Apy₃ has high concentrations of S, Fe, and Sb, which is consistent with element patterns in associated main and late ore stage pyrite generations. Compared with pyrite from other stages, the post-ore stage Py₄ has relatively low concentrations of Fe and S, whereas As remains elevated (2.05～3.20 wt%), which could be interpreted by the substitution of As^? for S in the pyrite structure. These results suggest that syngenetic/diagenetic pyrite is the main metal source for the Yangshan gold deposits where such pyrite was metamorphosed at depth below presently exposed levels. The ore-forming elements were concentrated into the hydrothermal fluids during metamorphic devolatilization, and subsequently, during extensive fluid–rock interaction at shallower levels, these elements were precipitated via widespread sulfidation during the main ore stage.     

Two types of multiple solutions for microseismic source location based on arrival-time-difference approach

The arrival-time-difference approach is the dominant source location approach used in the microseismic source location area. Multiple solutions problem is one of the major concerns in microseismic source location, which is closely related to the microseismic network. This paper categorizes the multiple solutions into two types based on the origin times when using the arrival-time-difference approach. Type I multiple solutions are those which have the same origin time; type II multiple solutions are those with different origin times. The sufficient and necessary conditions to produce type I multiple solutions are that all sensors are located in a straight line for two-dimensional cases and on a plane for three-dimensional cases. The sufficient and necessary conditions to produce type II multiple solutions are that all sensors are located on a hyperbola for two-dimensional cases and on a hyperboloid for three-dimensional cases. Furthermore, the proofs indicate that type I multiple solutions are preventable, while a microseismic network consisting of the minimum number of sensors can never be free of type II multiple solutions. It means, besides the minimum number of sensors, at least one more sensor which is not on this hyperbola or hyperboloid is needed to uniquely determine a source. The results from field tests and applications indicate that when the sensors of a network lie on a hyperbola, the type II multiple solutions may not be the necessary outcome under the influence of errors in real data. However, the accuracy of the microseismic source location is affected significantly by this kind of networks. The results also show that not only the multiple solutions problem can be avoided effectively, but more importantly, the accuracy of the source location will be greatly improved by the optimization of network based on the characteristics of the microseismic network and field conditions.     

Synthesis and Characterization of an Extractant [Bmim]PF_6 for Lithium Ion

正With the rapid increasing demand of metal lithium and its compounds in science and technology,studies on lithium recovery though lithium ion extraction from salt lake brines are blooming bacause more than 60 percent of     

松嫩平原(吉林省)地下水动态特征及类型的研究

根据松嫩平原(吉林省)地下水动态观测资料进行分析,对区内的主要供水含水层的动态特征进行了描述,并对其进行了动态类型的划分,结合地下水动态的主要影响因素将为研究区地下水动态预测及地下水资源管理提供了依据。     

提高矿区开采沉陷变形监测快速定位精度方法探讨

为提高矿区开采沉陷变形监测GPS-RTK快速定位的精度,通过对GPS-RTK基准站位置的选取和转换参数选择的实验,研究在使用GPS-RTK进行测量的过程中,提高在矿区开采沉陷变形监测中GPS-RTK快速定位测量的数据精度,并用实例与E级GPS网获取的静态定位数据进行对比,实验证明可以达到一级导线的精度要求。     

冰后回弹对全球及中国参考框架的影响分析

文章利用ICE-5G模型发布的最新预报值,计算分析了冰后回弹对全球和中国区域的影响,发现冰后回弹不仅会引起垂直方向的地壳运动,而且还会引起水平方向的地壳运动,但是水平方向的量级要明显小于垂直方向.全球范围内最大回弹区域位于加拿大,大约为16mm/a,而由冰后回弹所引起的地壳水平方向运动达3mm/a.这个回弹量级对于维持毫米级ITRF的稳定所造成的影响是不容忽视的.中国范围内回弹值大概在0～0.7mm/a,这个量级对于参考框架的影响基本可以忽略.     

Study of Distinctive Regional Features of Surface Solar Radiation in North and East China

Solar radiation is an important energy source for plants on the earth and also a major component of the global energy balance.Variations in solar radiation incident at the earth's surface profoundly affect the human and terrestrial environment,including the climate change.To provide useful information for predicting the future climate change in China,distinctive regional features in spatial and temporal variations of the surface solar radiation (SSR) and corresponding attributions (such as cloud and aerosol) are analyzed based on SSR observations and other meteorological measurements in North and East China from 1961 to 2007.Multiple models,such as the plane-parallel radiative transfer model,empirical and statistical models,and corrclation and regrcssion analysis methods are used in the study.The results are given as follows.(1) During 1961-2007,the total SSR in North China went through a process from quickly “dimming” to slowly “dimming”,while in East China,a significant transition from “dimming” to “brightening” occurred.Although there are some differences between thc two regional variation trends,long-term variations in SSR in the two regions are basically consistent with the observation worldwide.(2) Between the 1960s and 1980s,in both North and East China,aerosols played a critical rolc in the radiation dimming.However,after 1989,different variation trends of SSR occurred in North and East China,indicating that aerosols were not the dominant factor.(3) Cloud cover contributed less to the variation of SSR in North China,but was thc major attribution in East China and played a promoting role in the reversal of SSR from dimming to brightening,especially in the “remarkable brightening” period,with its contribution as high as 70％.     

南黄海盆地北部坳陷正反转构造

南黄海盆地北部坳陷的东北凹、北凹、中凹、南凹等凹陷发育有多种类型的正反转构造,包括穿透断展型、挤压褶皱型、逆断层型等。主要反转期为渐新世和上新世末,其中渐新世的构造反转影响较大。太平洋—欧亚板块汇聚速率变化是控制南黄海盆地北部坳陷新生代反转构造发育的重要因素。正反转构造有利于油气藏的形成,但反转强度较大时可能使油气藏的保存条件变差。     

巨分子云聚合形成N体模拟中粒子数的效应

通过N体数值模拟以不同粒子数对星系中巨分子云的形成的影响进行了研究。结果表明：在聚合形成机制下，当对不同数目的分子云取相同的平均密度时，基本分子云的有效半径与其相应质量的立方根成正比，巨分子云的碎裂率与模拟基本分子云的数目无关。