威海地区榴辉岩及其变质作用

威海地区榴辉岩位于秦岭大别苏北胶南巨型榴辉岩带的北东段。榴辉岩体大小悬殊,呈透镜状、不规则状、脉状及似层状等赋存在早元古代荆山岩群变质层状岩系、尖晶石橄榄透闪片岩及晚元古代片麻状花岗闪长岩、片麻状二长花岗岩中,并与围岩一起经受了后期的构造变形改造。榴辉岩退变分带的核部为榴辉岩,次外边为榴闪岩,最外边为斜长角闪岩或石榴斜长角闪岩。三个变质作用阶段的特征是：前榴辉相阶段为中压相系绿帘角闪岩相;榴辉岩相阶段为高压相系;榴辉岩退变质阶段相当于中压相系的角闪麻粒岩相—角闪岩相。变质作用ＰＴｔ轨迹呈顺时针方向。榴辉岩形成于９００Ｍａ左右。     

Hydrogeochemical Processes and Quality Assessment of Groundwater in Sulin Mining Area,Northern Anhui Province,China

Water Resources - In mining areas, coal production, agriculture, and drinking use had increased the demand for fresh groundwater. It was essential to obtain a deeper understanding of the...     

Geochemistry,U–Pb Geochronology and Hf Isotope Studies of the Daheishan Porphyry Mo Deposit in Heilongjiang Province,NE China

The Daheishan porphyry Mo deposit was recently discovered in the northern segment of the Great Xing'an Range, NE China. Three main types of granitoids are identified in this deposit: granodiorite, fine‐grained granite, and porphyritic granite. The orebodies are dominantly hosted within the granodiorite and in the contact zone between the granodiorite and tuff or hornfels, while no mineralization has been found in the fine‐grained granite or the porphyritic granite. We present in situ LA‐ICP‐MS zircon U‐Pb dates for the granodiorite, fine‐grained granite, and porphyritic granite, which yielded 146.9 ± 1.1 Ma (2σ), 146.6 ± 1.7 Ma (2σ), and 149.7 ± 4.2 Ma (2σ), respectively. Their ε_Hf(t) values range from 3.9 to 12.2, associated with young crustal model ages (T_DM2) ranging from 524 Ma to 849 Ma, indicating that their parental magmas may have been generated by partial melting of the Neoproterozoic–Cambrian crustal components. The formation of the Daheishan deposit was genetically related to the subduction of the Paleo‐Pacific Plate.     

Quantitative analysis of the driving forces causing declines in marsh wetland landscapes in the Honghe region, northeast China, from 1975 to 2006

The Sanjiang Plain has the most representative and largest concentration of inland freshwater wetlands in China, most of which have been degraded or have disappeared as a result of agricultural development and climatic change since the 1950s. To better understand the spatial and temporal variation and driving forces of marsh reduction, this study investigated variations of marsh reduction in the Honghe region of the Sanjiang Plain, Northeast China over a 30-year period, and analyzed the role of the different driving forces separately and their combined effect on marsh reduction and identified what driving forces have played key roles on the reduction in different periods. Nine natural and anthropogenic variables from remote sensing, GIS data and field surveys, such as precipitation, temperature, precipitation anomaly, population density, agricultural population density, per capita GDP, distance to road, distance to canal and distance to settlement, were evaluated on their impact on observed variations of marsh reduction between 1975 and 2006. The results show that all of these driving forces have significant influences on the decline of the marsh area, and the combination of driving forces that has crucial impacts on marsh reduction varied largely from 1975 to 2006. During 1975–1989, it was the construction of canal and road networks in farms and changes in average annual precipitation that led to marsh reduction. After 1989, the reduction was mainly related to increases in agricultural population, per capita GDP and settlements. These findings may help understand the declines or degradation of marsh areas and provide an empirical and theoretical base for managers, who design and implement wetland management and planning.     

Effects of salt solutions on the hydro-mechanical behavior of compacted GMZ01 Bentonite

In this study, the effects of salinity of infiltrating solutions on the swelling strain, compressibility, and hydraulic conductivity of compacted GMZ01 Bentonite were investigated. After swelling under vertical load using either distilled water or NaCl solutions with concentrations of 0.1, 0.5 M, and 1 M, laboratory oedometer tests were conducted on the compacted GMZ01 Bentonite. Based on the oedometer test results, hydraulic conductivity was determined using the Casagrande’s method. Results show that the swelling strain of highly compacted GMZ01 Bentonite decreases as the concentration of NaCl solution increases. The compression index C _c ^* increases and then turns to decrease with an increase in the vertical stress or a decrease in the void ratio for different solutions, and the C _c ^* decreases as the concentration of NaCl solution increases. The secondary consolidation coefficient C _α increases linearly with the increase of the compression index C _c ^* . Furthermore, a bi-linear relationship between the swelling index C _s ^* and the secondary consolidation coefficient C _α can be characterized clearly. The hydraulic conductivity increases as the concentration of NaCl solution increases, however, this increase can be prevented if a high confining stress is applied.     

Identification and geochemical significance of polarized macromolecular compounds in lacustrine and marine oils

Polarized macromolecular compounds in typical lacustrine and marine shale oils collected from the Ordos Basin and Tarim Basin of China were analyzed by FT-ICR-MS. Maturity was taken into consideration by diagenesis physical simulation experiments on shale oils, which had been collected at various temperature and pressure stages. The results showed that similar components existed in non-hydrocarbon and asphaltenes and the main peak compound classes of Nl and 02 were potential parameters for identifying typical marine oil and lacustrine oil in China. Nitrogen compounds/（nitrogen compounds and oxygen compounds）, such as Nl/（O2＋Nt）, NL/（Oa＋Nt）, Ni/（NiO1＋N1O2） are the maturity indicators, which are related with C-N and C-O bond energy. Differences in molecular components and weights between marine and lacustrine oils are the effective index to identify source maturity and sedimentary environment.     

陕西镇安县太白庙一带金矿地质特征及控矿因素

镇安县太白庙一带金矿以显微金与明金颗粒为特征,矿床由三个近东西向展布的含金石英脉体密集带构成,由南向北可划分为Ⅰ、Ⅱ、Ⅲ三个含矿带。赋矿地层为泥盆系星红铺组,金矿矿(化)体分布受地层、构造双重控制。     

内蒙古额仁陶勒盖银矿区火成岩岩石地球化学特征及锆石SHRIMPU-Pb同位素定年

通过对额仁陶勒盖银矿区的塔木兰沟组中酸性火山岩详细的岩石地球化学特征研究表明,该套火山岩具高硅(SiO₂>57%)、高铝(Al₂O₃>16%)、富碱尤其富钾(K₂O>3%)特征,属HKCA系列;稀土含量中等(187×10^-6~240×10^-6),(La/Yb)_N在18.6~27.9,Yb<1.90×10^-6,Y<18.0×10^-6,δEu=0.85~0.96,轻重稀土分馏强烈,明显亏损重稀土,无或略具负铕异常;微量元素相对富集Rb、Ba、Th、U、K等大离子亲石元素(LILE),亏损高场强元素Nb、Ta、Ti、HREE,与活动陆缘火成岩的微量元素特征一致.塔木兰沟组安山质火山岩特征表明,安山质岩浆来源较深(>50km),起源于加厚地壳底部,源区残留为石榴石、单斜辉石及角闪石,岩浆在部分熔融及后期演化过程中不曾与斜长石平衡过,可能是蒙古-鄂霍茨克洋闭合后进入碰撞后松弛阶段,钙碱性或高钾钙碱性的中基性变火成岩的部分熔融形成.对与额仁陶勒盖银矿关系密切的石英斑岩(脉)测年,获得SHRIMP U-Pb年龄138.6±2.3Ma,为石英斑岩的成岩年龄,进一步限定该银矿床形成于早白垩世早期.对塔木兰沟组安山岩与石英斑岩成岩年龄、矿床成矿特征等方面进行探讨了,认为该银矿床为岩浆热液成因.     

Sudden surface collapse disasters caused by shallow partial mining in Datong coalfield,China

Numerous sudden surface collapses induced by shallow partial mining in the Datong Jurassic coal seam have caused fatalities, significant property losses and brought about harmful results to the environment. By introducing efficient pillar widths and using the Voronoi diagram, irregular pillar stability can be estimated rationally. Theoretical analysis and numerical simulation demonstrate that the failure of a single pillar increases the load on surrounding pillars. If the magnitude of the transferred load is sufficiently high, the adjoining pillars will also fail in a chain reaction. This can be interpreted by the merger of inner stress arches combined with the external stress arch. In this paper, the evolution mode of sudden surface collapse caused by shallow partial mining is proposed and has been verified by ‘similar material simulation.’ Finally, the potential of sudden surface collapse is determined and an example of collapse prediction and prevention of surface building damage with relocation is given.     

CPT-Based estimation of undrained shear strength of fine-grained soils in the Huanghe River Delta

The Huanghe River（Yellow River） Delta has a wide distribution of fine-grained soils. Fluvial alluviation, erosion,and wave loads affect the shoal area, resulting complex physical and mechanical properties to sensitive fine-grained soil located at the river-sea boundary. The cone penetration test（CPT） is a convenient and effective in situ testing method which can accurately identify various soil parameters. Studies on undrained shear strength only roughly determine the fine content（FC） without ma...