塔里木盆地古城地区鹰山组白云岩稀土元素地球化学特征及成因

白云岩成因一直是地质学研究的热点领域。塔里木盆地塔东低隆起古城低凸起中—下奥陶统鹰山组发育厚层白云岩。为研究这些白云岩的成因,在岩心、薄片观测基础上,按照晶体粒度大小将白云岩分为泥晶白云岩、粉晶白云岩、细晶白云岩、中晶白云岩、粗晶白云岩,并对各类白云岩及缝洞充填物进行了稀土元素地球化学特征的研究。结果表明,各类白云岩及缝洞充填物稀土元素NASC配分模式分为6种类型：δCe弱正异常δEu正异常型、δCe负异常δEu强正异常型、δCe强负异常型、微右倾型、微左倾型和平坦型。分析上述6种白云岩及缝洞充填物的成因为：前2种类型形成于两期热液或不同演化阶段的同一期热液环境;第3种类型形成于蒸发泵模式;第4和第5种形成于两种性质不同的埋藏白云化流体;第6种则由渗透回流作用形成。古城地区鹰山组白云岩的成因非常复杂,成因模式多样,包括蒸发泵模式、渗透回流模式、埋藏白云化模式、热液白云化模式4种。     

波浪水槽中振动格栅湍流特征的实验研究

在波浪水槽中采用格栅振动的方式产生湍流,研究振动格栅产生湍流的特征。本文开展了4类实验,调节测量点到格栅平均位置的距离、格栅振动频率、振动冲程,采用ADV测量水体中单点的脉动速度。实验结果显示,湍流强度在一定范围内随离格栅距离的增大而逐渐减小,随着振动频率的增大而呈幂指数增大,随着振动冲程的增大而呈幂指数增大。同时还比较了两个不同格栅产生湍流的不同。结果显示,在波浪水槽中,振动格栅产生湍流的强度还与格栅的长度尺寸有关,这与在水箱中振动格栅产生湍流的特征不同。     

海门一次F1级龙卷的多普勒天气雷达特征分析

用多普勒天气雷达、常规观测和地面加密观测资料对2011年7月13日发生在江苏南通海门市树勋镇的龙卷风过程进行了详细分析。得出:较长时间的不稳定层结的存在,较低的抬升凝结高度,较强的水平和垂直风切变以及地面干线的存在为龙卷风的发生发展提供很好的动力条件;底层冷空气的切入,较强的风切变易使单体发展更加旺盛。强回波中心高度和垂直积分液态含水量的下降,径向速度风场中气旋性涡旋的迅速发展是对龙卷风提前警戒的很好指标。龙卷风进行过程中,此系统为低位质心的对流系统,产生的天气是龙卷,伴随大风,与冰雹的高位质心对流系统有明显的区别。中气旋高度,最大切变高度的骤降,中气旋尺度的急剧收缩预示着龙卷的发生,为我们今后的龙卷风预警提供有利的参考。     

Kinetics of Hydrothermal Reactions of Minerals in Near-critical and Supercritical Water

This work presents new experimental results on the kinetics of mineral dissolution in near-critical and supercritical water in a temperature range (T) from 25 to 400℃ and a constant pressure of 23 MPa. Kinetic experiments were carried out by using a flow reactor (packed bed reactor) of an open system. The dissolution rates of albite and magnetite were measured under these experimental conditions. Na, Al and Si release rates for albite dissolution in water were measured as a function of the temperature and flow velocity in the reaction system. The maximum release rates of Na, AI and Si of albite dissolution in the hydrothermal flow systems under different flow velocities were always obtained at 300℃, that is to say, the maximum albite dissolution rates in the flow systems, regardless of different flow rates, were repeatedly measured at 300℃. Results indicate a wide fluctuation in albite dissolution rates occurring close to the critical point of water. The dissolution rates increased when the temperatu     

金伯利岩体上中梯装置ρ_s异常的性态研究

简要介绍了边界单元法的计算原理,以直立圆柱、圆台、蘑菇状模型模拟不同形态的金伯利岩体,用边界单元法对上述模型的中梯装置ρ_3异常进行了正演计算。着重对正演计算结果进行分析,总结出不同条件下ρ_3曲线的性态特征,所得规律有利于进一步改善中梯装置电阻率法在勘查金伯利岩中的应用效果。     

A case study of the influx of upper mantle fluids into the crust

Geochemical and geophysical investigations in the Bohai Gulf and adjacent areas, China, indicate that uplift of the high-conductivity layer in the lithosphere coincides with the area of high heat flow. In this area are distributed abundant oil and gas fields in a Tertiary fault basin and also large quantities of basaltic rocks. Gas fields, mostly CO₂ bearing, occur at the basin margins, where a widespread alkaline olivine basalt has high contents of gold. Geochemical prospecting of the surface (soil and soil gas) in the area indicates that there is an anomaly zone of large-scale gold mineralization, and large gold deposits have been found in this area. Isotopic study demonstrates that CO₂ in the volcanic rocks and in the CO₂-bearing gas deposits are all derived from the mantle. Experiments show that Au- and CO₂-bearing hydrothermal fluids separated into vapor phase and liquid phases respectively due to a reduction of pressure and temperature over the temperature range from 250 to 290°C and at 22 M Pa. Au appears in the vapor phase rich in CO₂. That proves that it is possible that CO₂-bearing aqueous fluids (in gas phase) can carry gold and transport it from deeper parts of lithosphere to the surface.     

台风尼伯特(1601)残留低压局地大暴雨成因分析

利用常规观气象观测资料、地面自动站资料、NCEP/FNL逐6h的1°×1°再分析资料、多普勒天气雷达和风廓线雷达资料及GPS-PWV资料等,对江苏南通2016年7月11日一次大暴雨到特大暴雨过程进行了分析。结果表明:(1)该过程发生在台风尼伯特(1601号)残留低压、高空冷涡低槽和副热带高压共同作用的背景下;台风残留低压北侧倒槽顶部大的气旋性曲率和高空槽前减压导致低层苏南附近α中尺度低压生成,台风残留低压并入该低压,使低压发展,气压梯度加大,气压梯度力做功使动能增大,导致低空西南急流形成,利于暴雨发生;α中尺度低压内先后有D1、D2和D3等3个β中尺度低涡生成,其中D3造成了南通地区的大暴雨,中心位于南通大学附近,最大雨强达151.2mm·h~(-1)。(2)南通地区对流风暴触发后,降水的凝结潜热释放增强了对流风暴内的上升运动,促使低空中尺度偏东急流和其左前侧β中尺度低涡D3的形成和发展;之后,中层干冷空气入侵加强了对流不稳定和垂直风切变,使D3右侧多个低质心的γ中尺度单体风暴强烈发展且受低空风影响移动缓慢,强降水得以持续和跃增。(3)风垂直切变突增时间较强降水出现峰值时间早约30min,以及多普勒天气雷达径向速度的低空辐合(辐散)较对流风暴的发展(减弱)明显提前,对临近预报有一定的参考意义。     

土壤中氡浓度检测及其影响因素

综合相关文献研究,通过工程实例介绍土壤中氡气浓度的检测方法,对检测结果进行统计学分析,根据分析结果探讨不同土壤中氡浓度差异及其影响因素。结果显示:土壤孔隙度是影响土壤中氡气浓度的关键因素。不同类型的表层土壤,孔隙度不同,所含氡气浓度也不同。当表层土壤为房渣土、填土时,土质夯实,孔隙率低,氡浓度含量较低;表层土壤为粉土、粉质粘土时,土质较均匀,土层较疏松,孔隙度略大,土壤氡浓度大于前者;表层土壤为粉砂、细砂时,土层更为疏松,土壤中孔隙度再次增大,氡在土壤中有大量的存储空间,所含的氡浓度最大。因此,土壤的孔隙度大小影响氡从地下向地表渗透析出的难易程度,孔隙度越大氡越容易渗透其中,浓度就越高。     

普通高中灾害地理教育课程:意蕴及校本构建

灾害地理教育主要培养学生对自然灾害的感受、理解以及人类与其理性相处和和谐共生的自觉意识和能力,为了便于灾害地理教育操作和实施,本文主要从三个维度,使学生理解自然灾害、环境与人类之间的关系,通过灾害地理教育课程校本建构,实现灾害知识接受学习和实践体验的无缝衔接,努力回答新时代灾害地理教育培养"什么样的人"这一问题。     

Shifting from homogeneous to heterogeneous surfaces in estimating terrestrial evapotranspiration: Review and perspectives

Terrestrial evapotranspiration(ET)is a crucial link between Earth’s water cycle and the surface energy budget.Accurate measurement and estimation remain a major challenge in geophysical,biological,and environmental studies.Pioneering work,represented by Dalton and Penman,and the development of theories and experiments on turbulent exchange in the atmospheric boundary layer(ABL),laid the foundation for mainstream methodologies in ET estimation.Since the 1990s,eddy covariance(EC)systems and satellite remote sensing have been widely applied from cold to tropical and from arid to humid regions.They cover water surfaces,wetlands,forests,croplands,grasslands,barelands,and urban areas,offering an exceptional number of reports on diverse ET processes.Surface nocturnal ET,hysteresis between ET and environmental forces,turbulence intermittency,island effects on heterogeneous surfaces,and phase transition between underlying surfaces are examples of reported new phenomena,posing theoretical and practical challenges to mainstream ET methodologies.Additionally,based on non-conventional theories,new methods have emerged,such as maximum entropy production and nonparametric approaches.Furthermore,high-frequency on-site observation and aerospace remote sensing technology in combination form multi-scale observations across plant stomata,leaves,plants,canopies,landscapes,and basins.This promotes an insightful understanding of diverse ET processes and synthesizes the common mechanisms of the processes between and across spatial and temporal scales.All the recent achievements in conception,model,and technology serve as the basis for breaking through the known difficulties in ET estimation.We expect that they will provide a rigorous,reliable scientific basis and experimental support to address theoretical arguments of global significance,such as the water-heat-carbon cycle,and solve practical needs of national importance,including agricultural irrigation and food security,precise management of water resources and eco-environmental protection,and regulation of the urban thermal environment and climate change adaptation.