Characteristics of the mantle source region of sodium lamprophyres and petrogenetic tectonic setting in northeastern Hunan,China

~~Characteristics of the mantle source region of sodium lamprophyres and petrogenetic tectonic setting in northeastern Hunan,China~~     

DINI11数字水准仪观测资料处理软件

介绍了编制DINI11数字水准仪观测资料后,处理软件的设计思路和实现方法,该软件自动完成观测资料入库、计算、打印手簿、成果表和画时序图等任务。     

河北平原地震带的现今活动性分析

根据近41年的现代地震资料,利用地震活动性参数组合、b值空间分布、断裂带分段,并结合历史强震构造背景的综合分析方法,分析河北平原地震带各分段现今地震活动习性和地震危险性.研究结果表明：河北平原地震带存在7个具有不同现今活动习性的分段,其中,唐山—迁安段和东明—阳谷段处于低b值、高应力状态,属于大震后晚期余震活跃或断层震后调整运动结果;昌平—宝坻、天津—肃宁段、新河段、邯郸—磁县及汤西段断层面现今活动习性均处于相对低应力下的频繁或稀疏小震滑动.因此,河北平原地震带未来短期内发生强震的可能性较小.     

Geological and geochemical characteristics of the Baogudi Carlintype gold district(Southwest Guizhou,China) and their geological implications

The newly discovered Baogudi gold district is located in the southwestern Guizhou Province,China,where there are numerous Carlin-type gold deposits.To better understand the geological and geochemical characteristics of the Baogudi gold district,we carried out petrographic observations,elemental analyses,and fluid inclusion and isotopic composition studies.We also compared the results with those of typical Carlin-type gold deposits in southwestern Guizhou.Three mineralization stages,namely,the sedimentation diagenesis,hydrothermal(main-ore and late-ore substages),and supergene stages,were identified based on field and petrographic observations.The main-ore and late-ore stages correspond to Au and Sb mineralization,respectively,which are similar to typical Carlin-type mineralization.The mass transfer associated with alteration and mineralization shows that a significant amount of Au,As,Sb,Hg,Tl,Mo,and S were added to mineralized rocks during the main-ore stage.Remarkably,arsenic,Sb,and S were added to the mineralized rocks during the late-ore stage.Element migration indicates that the sulfidation process was responsible for ore formation.Four types of fluid inclusions were identified in ore-related quartz and fluorite.The main-ore stage fluids are characterized by an H2O–NaCl–CO2–CH4±N2system,with medium to low temperatures(180–260℃)and low salinity(0–9.08%NaCl equivalent).The late-ore stage fluids featured H2O–NaCl±CO2±CH4,with low temperature(120–200℃)and low salinity(0–7.48%Na Cl equivalent).The temperature,salinity,and CO2and CH4concentrations of ore-forming fluids decreased from the main-ore stage to the late-ore stage.The calculated δ^13C,d D,and δ^18O values of the ore-forming fluids range from-14.3 to-7.0%,-76 to-55.7%,and 4.5–15.0%,respectively.Late-ore-stage stibnite had δ^34S values ranging from-0.6 to 1.9%.These stable isotopic compositions indicate that the ore-forming fluids originated mainly from deep magmatic hydrothermal fluids,with minor contributions from strata.Collectively,the Baogudi metallogenic district has geological and geochemical characteristics that are typical of Carlin-type gold deposits in southwest Guizhou.It is likely that the Baogudi gold district,together with other Carlin-type gold deposits in southwestern Guizhou,was formed in response to a single widespread metallogenic event.     

Numerical modeling of free surface flow over submerged and highly flexible vegetation

Vegetation in rivers, estuaries and coastal areas is often submerged and highly flexible. The study of its interaction with the ambient flow environment is important for the determination of the discharge capacity, morphological characteristics and ecological conditions of the water course where it grows. In this work the hydrodynamics of submerged flexible vegetation with or without foliage is investigated by using a 3D numerical model. Flexible vegetation is modeled by momentum sink terms, with the velocity-dependent stem height determined by a large deflection analysis which is more accurate than the previously used small deflection analysis. The effect of foliage on flow resistance is expressed in terms of the change in the product of the drag coefficient and the projected area, which is supported by available experimental data. The computed results show that the vertical profiles of the mean horizontal velocity and the vertical Reynolds shear stress are correctly simulated. The temporal variation of the stem deflection follows closely that of the velocity and the ‘Honami’ phenomenon can be reproduced. The numerical simulations also confirm that the flexibility of vegetation decreases both the vegetation-induced flow resistance force and the vertical Reynolds shear stress, while the presence of foliage further enhances these reduction effects.     

海南琼海加积井水温同震效应特征和机理初探

基于海南加积井数字化水温2007年1月-2010年4月震中距小于8 000 km、Ms≥7.8大震的同震响应资料,系统分析水温年月日正常动态特征,发现远震引起的水温同震效应特征为上升脉冲,与以往的非自流井水温同震效应以下降为主的认识不一致;水温变化幅度与震中距、震级有一定关系,加积井水温同震效应成因,可用“层内混合”作...     

泉州地震台测震观测质量分析及技术对策

通过对泉州地震台甚宽频带数字地震仪测震观测的台基地动噪声、监测能力、震级偏差和震相特征分析等方面的综合研究,提出了减少测震台基地动噪声影响、提高测震监测能力、减少震级偏差、提高震相分析水平、加强观测系统的维护、提高测震速报与地震编目的水平及规范观测质量的管理等方面相应的技术对策,有关研究结果对寻求和提高泉州台测震观测质...