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Li Nan Li Baolin Chen Dong Wang Enyuan Tan Yuyang Qian Jiawei Jia Haishan 《Natural Resources Research》2020,29(6):3653-3674
Natural Resources Research - Some industrial activities, such as underground mining, hydraulic fracturing (HF), can cause microearthquakes and even damaging earthquakes. In recent years, with the... 相似文献
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ZHAO Haitong ZHANG Yongsheng XING Enyuan WANG Linlin GUI Baoling SHANG Wenjun PENG Yuan SHI Lizhi 《《地质学报》英文版》2018,92(1):418-419
正Objective The Ordovician Shaanxi salt basin is located in the junction of the North China Sea and the Qilian Sea.In this basin the Majiagou Formation accumulated more than1000m thick evaporite-carbonate sediments,and this basin is divided into east and west saltern sags(ESS,WSS)according to the characteristics of geochemical analysis(Zhang Yongsheng et al.,2014).Isotope stratigraphy of evaporite sediments represents a fundamental tool in 相似文献
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南海东北部深部地壳结构蕴含着南海陆缘伸展张裂过程的重要信息。在南海东北陆缘布设的一条广角地震测线(DP13)沿NW-SE方向依次穿过东沙隆起和台西南盆地。本文利用射线追踪和正演走时拟合软件RayInvr构建地壳纵波速度结构,模型表明：沉积层速度1.6～4.6 km/s,厚度0.5～3.8 km,横向分布不均匀,沉积基底起伏剧烈;莫霍面埋藏深度由陆架区的25.5 km急剧减小到陆坡下方的13 km,随后向下陆坡远端增深至16 km;陆架处东沙隆起下方地壳厚度从～25 km减薄到～21 km,下陆坡远端地壳厚约10～13 km,地壳拉张因子分别为1.3～1.5和2.6～3.1,表现为轻微和中等减薄;陆坡区台西南盆地内地壳厚度从17 km急剧减薄至7～8 km,地壳拉张因子高达4.6,呈超伸展减薄;地壳厚度由陆向海非单调减薄,地壳伸展具有明显的空间差异性;陆架-上陆坡和下陆坡下地壳底部发现两个相对孤立的不连续高速体,速度分别为7.0～7.5 km/s和7.0～7.3 km/s,厚度分别3～5 km和1～3 km,前者位于古太平洋俯冲带前缘,几乎与南海东北部高磁异常重叠,推测由中生代古太平洋板... 相似文献
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扎拉格阿木铜矿床位于锡林浩特地块北部边缘,矿体赋存于二叠纪砂质板岩和角砾岩中,受NE向断裂控制,为中温热液脉型铜矿床。本文通过流体包裹体和C?H?O?S?Pb同位素地球化学研究手段,来探讨扎拉格阿木铜矿成矿机制。成矿热液期存在5个成矿阶段：钾长石阶段、石英?绢云母阶段、石英?黄铁矿阶段、石英?多金属硫化物阶段、石英?方解石阶段。其中石英?多金属硫化物阶段为主成矿阶段,本阶段主要发育富液相、富气相、含子矿物包裹体;富液相包裹体均一温度与盐度分别为：138～289℃和2.06%～16.11% NaCl eqv;含子矿物包裹体均一温度与盐度分别为：320～374℃和32.68%～39.81% NaCl eqv,包裹体气体成分除少量CO2以外,均为H2O。H?O同位素分析表现为,石英中的〖δO〗^18值变化范围－8.5‰～7.5‰,流体的δD值变化范围为－116‰～－98‰,暗示早阶段成矿流体主要为岩浆热液,晚期伴有大气降水混入。C?O同位素分析表明,δ13C值为-6.9‰~ -10.1‰,δ18OSMOW介于2.5‰~11.7‰,在δ18O?δ13C 图上数据点落在岩浆水与大气水的中间区域。矿石硫化物的δ34S值介于-4.5‰~1.5‰,指示具有幔源岩浆硫的特征。矿石硫化物Pb同位素的208Pb/204Pb、207Pb/204Pb和206Pb/204Pb比值分别为38.034~38.609、15.497~15.655和18.141~18.446,推测Pb具有地幔来源的特点并伴有地壳或造山带Pb混入。成矿过程中伴随着流体沸腾作用,成矿物质沉淀受早期形成的岩浆热液与后加入大气降水混合的影响。 相似文献
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陕北奥陶纪盐盆位于鄂尔多斯盆地伊陕斜坡东部。研究表明:马五6亚期,盐盆存在"两坳一隆"的构造格局,即东、西部盐坳和中部隆起,东、西部盐坳在钾矿化情况、溴氯系数反映的水体咸化趋势方面初步显示了陕北盐盆东、西部沉积环境的差异。本文通过东、西部盐坳典型钻井马五6层位沉积学分析,揭示了马五6时期东、西部盐坳在水体深度变化、浓缩趋势、含钾量、淡化层段厚度、陆源物质输入方面均存在差异。其中,西部盐坳受海水影响大,水体变浅且持续淡化,泥质分布反映陆源物质贡献少,对钾盐的沉积与保存均十分不利。而东部盐坳受海水影响小,与西部盐坳水体联通性差,在马五6时期环境更为封闭,具体表现为淡化夹层分布数量少、厚度薄的特征;水体持续变深并浓缩咸化;泥质夹层较多,反映了相较于西部,陆源物质对其影响更大,上述特点为钾盐沉积提供了有利的地球化学条件及可容空间。东、西部盐坳沉积环境对比表明东部盐坳对成钾更为有利。 相似文献
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柴西地区南翼山构造上新统混积岩中含有大量盐类矿物,其物源分析对盐矿物质来源研究有一定的参考价值。本文在野外观察和镜下鉴定的基础上,对南翼山构造上新统狮子沟组混积岩的地球化学特征进行了分析,并结合周缘造山带花岗岩的稀土元素数据,探讨了混积岩中陆源碎屑的物质来源。结果显示：南翼山构造狮子沟组混积岩中碎屑矿物、碳酸盐矿物和黏土矿物呈均匀混合的状态,元素含量与矿物组分密切相关,除Ca、Na、Sr元素外,其余元素含量普遍低于上地壳平均含量,其中CaO和Na2O受碳酸盐和石盐形成影响,不能用于判别构造背景,而Sc、Th、Zr、Hf等微量元素和稀土元素较完整地保留了源岩的地球化学信息,可用于源区构造背景的判别及物源示踪,同时稀土元素配分模式一致性较好,表明混积岩中陆源碎屑具有相同的物源特征。稀土元素配分模式、La Th Sc、Th Sc Zr/10、La/Th Hf图解以及Al2O3/TiO2比值共同指示南翼山混积岩的陆源碎屑组分来源于大陆岛弧背景下的长英质火成岩,通过与周缘造山带花岗岩稀土配分模式对比,推断晚志留世和晚二叠世花岗岩是混积岩中陆源碎屑和盐类矿物的主要源岩,南部的祁漫塔格是主要的物源区,且西部的阿尔金南段也有部分物源贡献。 相似文献
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Shaobin Hu Enyuan Wang Zhonghui Li Rongxi Shen Jie Liu 《Rock Mechanics and Rock Engineering》2014,47(5):1821-1838
Dynamic collapses of deeply mined coal rocks are severe threats to miners. To predict the collapses more accurately using electromagnetic radiation (EMR), we investigate the time-varying multifractal characteristics and formation mechanism of EMR induced by underground coal mining. A series of uniaxial compression and multi-stage loading experiments with coal samples of different mechanical properties were carried out. The EMR signals during their damage evolution were monitored in real-time; the inherent law of EMR time series was analyzed by fractal theory. The results show that the time-varying multifractal characteristics of EMR are determined by damage evolutions process, the dissipated energy caused by damage evolutions such as crack propagation, fractal sliding and shearing can be regard as the fingerprint of various EMR micro-mechanics. Based on the Irreversible thermodynamics and damage mechanics, we introduced the damage internal variable, constructed the dissipative potential function and established the coupled model of the EMR and the dissipative energy, which revealed the nature of dynamic nonlinear characteristics of EMR. Dynamic multifractal spectrum is the objective response of EMR signals, thus it can be used to evaluate the coal deformation and fracture process. 相似文献
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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. 相似文献
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Wan Guojiang Zheng Xiangdong Lee H N Bai Z G Wan Enyuan Wang Shilu Yang Wei 《地球科学进展》2010,25(5):492-504
It′s essential to measure air concentrations and depositional fluxes of environmental radionuclides in different regions for modeling global contamination transfer and validation, tracing deposition process and dating, referencing watershed erosion trace and assessing natural radiation of ecosystem. This study introduces the research background and methods and explains weekly variations of 210Pb and 7Be concentrations in surface air and precipitation at Mt. Guanfeng/Guiyang since 2001. The results indicate that 210Pb and 7Be concentrations in surface air fluctuate periodically at 2~6 week interval because of the meteorological condition changes. The annual trend in 210Pb air concentration is overall influenced by air temperature variation and periodical rainfall. 7Be air concentration varies up and down regualarly. The synchronization of low concentrations for both 210Pb and 7Be in surface air and high ratio (210Pb/7Be ≥ 0.8) indicate oceanic poor 210Pb-7Be air mass invasion. The synchronization of high concentrations of 210Pb and 7Be in surface air and low ratio (210Pb/7Be ≤ 0.7) implies rich 7Be air mass invasion from altostratus atmosphere. Weekly concentrations of 210Pb and 7Be in precipitation and the Kd coefficients are high in late Autumn to Spring, and low in late Spring to Autumn. Although 210Pb and 7Be concentrations vary seasonally, their weekly concentrations in precipitation increase with that of air concentration. The 210Pb and 7Be weekly concentrations for seasonal division is about 0.2 Bq/L and 1 Bq/L, respectively. However, the Kd coefficient decreases when 210Pb and 7Be air concentrations increase. Deposition of 210Pb and 7Be with precipitation mainly take place in Spring and Summer; The weekly fallout of 210Pb and 7Be increases with increasing precipitation; the increase of 7Be is triple of that of 210Pb and 2.5 when precipitation nears to zero. The weekly-high fallout of 210Pb and 7Be with precipitation corresponds with the dramatic decrease of their air concentrations within or vicinal weeks. The ratio of 210Pb to 7Be in rainfall is overall ≤ 0.5 and varies synchronously with the ratio in surface air, indicating that the two radionuclides are cleaned by precipitation from air at close speed. In the extreme freezing disaster in 2008, both 210Pb and 7Be air concentrations were low and coupling with coexist of low concentration of aerosol and high nuclides activities. Weekly concentration of 7Be in surface air at Mt. Guanfeng demonstrates the anticipated concentration level in the low-latitude and high-elevation region; the short-term fluctuations of 7Be concentration indicated the hysteresis was influcenced by the strong air current submersion and the low-elevation air mass rising differently at Mt. Guanfeng and Mt. Waliguan. 相似文献