The effect of Newtonian cooling on vertically propagating magneto-acoustic waves in a thermally conducting isothermal atmosphere (II)     

Hadi Alkahby 《地球物理与天体物理流体动力学》2013,107(4):335-346

In this article, we examine reflection, dissipation and attenuation of vertically propagating waves in an isothermal atmosphere under the combined effect of Newtonian cooling, thermal conduction and viscosity with a weak horizontal magnetic field. We consider the case in which the combined effect of viscosity and magnetic field is dominated by that of the thermal conduction and for small values of the Newtonian parameter. As a result, the atmosphere can be divided into three distinct regions that are connected by two transition regions. The lower and middle regions are connected by a semi-transparent barrier and the middle and upper regions are connected by an absorbing and reflecting barrier. In the connecting barriers the reflection and transmission of the waves takes place. The presence of Newtonian cooling effects on the adiabatic region, produces attenuation in the amplitudes of the waves and reduces the energy absorption in the transition regions. The reflection coefficient is determined in the lower and middle regions and the results are discussed in the context of the heating of the solar atmosphere.  相似文献   

山东省矿产资源的可持续利用概要     

乔恩光 《山东国土资源》1999,(3)

山东是矿业大省，矿产地质工作程度较高，但在国民经济中占有重要位置的４５ 种主要矿产仅有８ 种能满足２０１０ 年本省经济建设的需求。针对矿产资源勘查、开发存在的主要问题，提出了全省矿产资源可持续利用战略目标及相应的对策建议  相似文献   

Surfaces of section in the Miranda-Umbriel 3:1 inclination problem     

Michèle Moons  Jacques Henrard 《Celestial Mechanics and Dynamical Astronomy》1994,59(2):129-148

The recent numerical simulations of Tittemore and Wisdom (1988, 1989, 1990) and Dermottet al. (1988), Malhotra and Dermott (1990) concerning the tidal evolution through resonances of some pairs of Uranian satellites have revealed interesting dynamical phenomena related to the interactions between close-by resonances. These interactions produce chaotic layers and strong secondary resonances. The slow evolution of the satellite orbits in this dynamical landscape is responsible for temporary capture into resonance, enhancement of eccentricity or inclination and subsequent escape from resonance. The present contribution aims at developing analytical tools for predicting the location and size of chaotic layers and secondary resonances. The problem of the 3:1 inclination resonance between Miranda and Umbriel is analysed.  相似文献   

青藏高原古近系牛堡组三段天文周期旋回分析及古湖平面演化研究：以尼玛盆地尼1井为例          下载免费PDF全文

陈云  伊海生  陈璐洁  伍新和  唐闻强  汪锐  杨芸  张承志 《沉积与特提斯地质》2023,43(3):555-564

青藏高原中部尼玛盆地是一个形成于班公湖-怒江缝合带之上的新生代陆相裂谷盆地。交通不便和勘探程度较低等因素导致其高精度沉积旋回特征和地层学一直鲜有研究。尼1井是盆地内第一口地质探井,通过对该井古近系牛堡组三段的自然伽马测井曲线进行频谱分析,证实了天文轨道周期对盆地内湖相地层的沉积具有显著影响。滤波分析显示牛堡组三段保存了41个短偏心率(～100 kyr)周期,76个斜率(～54 kyr)周期和178个岁差(～23 kyr)周期,平均沉积速率为92.03m/Ma,沉积时限～4.1 Myr。此外,结合Fischer图解与总有机碳含量的变化趋势,确定牛堡组三段湖平面经历了1次长周期的升-降变化过程。综合分析,认为尼玛盆地优质烃源岩的形成主要受天文旋回周期影响下的湖平面变化所控制。  相似文献   

基于深部地球物理信息的构造变形岩相分类研究     

张宝林  吕古贤  余建国  梁光河  李志远  徐兴旺  胡宝群  王红才  毕珉峰  焦建刚  王翠芝 《地学前缘》2022,29(1):413-426

“构造变形岩相”填图方法的创立和应用为老矿区深部及外围的找矿工作指明了方向,在实践中取得了显著的效果,需要大力推广和深入研究。对于构造变形岩相带的深部结构认识,需要依靠地球物理信息的解译。与地球物理场性质相类似,构造变形岩相带也是一个现存的地质体;物探工作目的是要探测和揭示构造变形岩相带的埋深、轮廓、内部结构构造等特征,为确定其形成时间和演化过程提供依据。由于地质与地球物理的复杂时空关系,如果仅以新鲜岩石标本物性参数的差异作为判别标志,难以提高地球物理方法的分辨率和有效性。结合构造变形岩相进行综合解译,更能提高解释推断成果的多学科融合性。作为终极勘探目标,需要紧密结合构造控矿级序,建立构造变形岩相带的三级分类标准,提取对应的地球物理信息:一级构造变形岩相带为目标物所处的构造单元及构造应力场,及其所对应的区域地球物理场特征,如隆凹构造相间的伸展构造域;二级构造变形岩相带为目标物所处的控矿构造体系,及其所对应的矿田地球物理场特征,如岩浆核杂岩隆起-拆离构造系统;三级构造变形岩相带为目标物所在的有利成矿构造部位,及其所对应于关键剖面的地球物理特征,如侵入岩体与围岩的接触带或者含矿断裂带等。选择国际流行的典型金属矿床类型,介绍了三级构造变形岩相带的地球物理组合信息特征及其分级利用操作流程,为有效应用地球物理勘探方法开展深部找矿预测提供了范例。  相似文献   

Holistic approach of GIS based Multi-Criteria Decision Analysis (MCDA) and WetSpass models to evaluate groundwater potential in Gelana watershed of Ethiopia          下载免费PDF全文

Niway Wondesen Fikade  Molla Dagnachew Daniel  Lohani Tarun Kumar 《地下水科学与工程》2022,10(2):138-152

Appropriate quantification and identification of the groundwater distribution in a hydrological basin may provide necessary information for effective management, planning and development of groundwater resources. Groundwater potential assessment and delineation in a highly heterogeneous environment with limited Spatiotemporal data derived from Gelana watershed of Abaya Chamo lake basin is performed, using integrated multi-criteria decision analysis (MCDA), water and energy transfer between soil and plant and atmosphere under quasi-steady state (WetSpass) models. The outputs of the WetSpass model reveal a favorable structure of water balance in the basin studied, mainly using surface runoff. The simulated total flow and groundwater recharge are validated using river measurements and estimated baseflow at two gauging stations located in the study area, which yields a good agreement. The WetSpass model effectively integrates a water balance assessment in a geographical information system (GIS) environment. The WetSpass model is shown to be computationally reputable for such a remote complex setting as the African rift, with a correlation coefficient of 0.99 and 0.99 for total flow and baseflow at a significant level of p-value<0.05, respectively. The simulated annual water budget reveals that 77.22% of annual precipitation loses through evapotranspiration, of which 16.54% is lost via surface runoff while 6.24% is recharged to the groundwater. The calibrated groundwater recharge from the WetSpass model is then considered when determining the controlling factors of groundwater occurrence and formation, together with other multi-thematic layers such as lithology, geomorphology, lineament density and drainage density. The selected five thematic layers through MCDA are incorporated by employing the analytical hierarchy process (AHP) method to identify the relative dominance in groundwater potential zoning. The weighted factors in the AHP are procedurally aggregated, based on weighted linear combinations to provide the groundwater potential index. Based on the potential indexes, the area then is demarcated into low, moderate, and high groundwater potential zones (GWPZ). The identified GWPZs are finally examined using the existing groundwater inventory data (static water level and springs) in the region. About 70.7% of groundwater inventory points are coinciding with the delineated GWPZs. The weighting comparison shows that lithology, geomorphology, and groundwater recharge appear to be the dominant factors influence on the resources potential. The assessment of groundwater potential index values identify 45.88% as high, 39.38% moderate, and 14.73% as low groundwater potential zones. WetSpass model analysis is more preferable in the area like Gelana watershed when the topography is rugged, inaccessible and having limited gauging stations.  相似文献   

Dating Neolithic rubble layers from Ba'ja and Basta sites in southern Jordan using luminescence     

《Quaternary Geochronology》2022

There is considerable evidence of widespread damage in the 7th millennium habitation sites across Jordan. The origins of this damage are unknown, but the most widely accepted hypothesis associates the resulting rubble and gravel deposits with the Holocene Rapid Climate Change. One way of testing the various hypotheses is to provide a more reliable chronology for the event(s) in question. In this study, we used quartz OSL and feldspar IRSL signals to date accumulative rubble layers at two archaeological sites in Southern Jordan; Ba'ja and Basta. By comparison with the OSL ages, the IRSL ages demonstrate that most of the quartz samples were sufficiently well bleached at deposition to provide accurate ages. Quartz ages show that deposition of the rubble layers took place in different episodes starting around 8.5 ka and 6.0 ka. Ages from Ba'ja site agree with the archaeological expectations of time of deposition. However, the results from Basta are younger than the archaeological expectations, which are based mainly on architectural style and stratigraphy.  相似文献   

甘肃北山前红泉地区水系沉积物地球化学特征及找矿方向     

陈世明  杨镇熙  雷自强  康维良  张晶  赵青虎 《现代地质》2022,36(6):1513-1524

前人在研究区开展过1∶20万水系沉积物测量及重砂测量,但受比例尺限制,异常面积过大,查证目标不够明确,找矿效果不佳。本次通过对前红泉地区开展1∶5万水系沉积物测量工作,初步总结了该区地球化学特征,根据元素组合特征、成矿地质条件等圈定出综合异常10处;在分析综合异常特征、异常检查情况及成矿潜力的基础上划分了成矿远景区4个,分别为受断裂和韧性剪切带控制的万岁山金成矿远景区、黑山头金多金属成矿远景区、与基性岩有关的帐房山铜钴镍成矿远景区及受酸性岩体内构造裂隙控制的红柳疙瘩钨成矿远景区;在成矿远景区内优选出找矿靶区4处,并提出了下一步找矿工作的建议。  相似文献   

黔西北地区土壤重金属地球化学背景及管理目标值     

孟伟  莫春虎  刘应忠 《物探与化探》2022,(1):250-257

基于贵州省毕节地区1∶25万土地质量地球化学调查的1 308件深层土壤样品重金属含量数据,研究了土壤重金属含量分布及其地球化学背景特征,与全国土壤比较,黔西北土壤重金属地球化学背景值显著高于全国土壤元素背景值,但是,与我国西南地区土壤元素背景值接近。黔西北地区土壤重金属含量与地质背景关系密切,不同地质单元区土壤重金属含量存在显著差异,石炭系地层发育的土壤呈Pb、Zn地球化学高背景,二叠系中统风化形成的土壤呈Cd、Hg地球化学高背景,黔西北地区不仅存在土法炼锌造成的土壤重金属污染,土壤重金属地球化学高背景也是影响土壤重金属富集的重要因素。统计表明,黔西北地区二叠系中统风化土壤Cd管理目标值高于我国农用地土壤Cd风险管制值(2.0×10^-6),认为在确定黔西北地区土壤重金属管理目标时,应充分考虑不同地质单元区土壤重金属地球化学背景值差异及其生态环境效应的影响。  相似文献   

阿尔泰可可托海伟晶岩中弧形石英白云母层的成因及意义   总被引：1，自引：0，他引：1  

田野  秦克章  周起凤  唐冬梅  王春龙 《岩石学报》2015,31(8):2353-2365

石英白云母层时常紧贴伟晶岩侵入体的边界出现且平行边界延伸。但是在新疆阿尔泰可可托海伟晶岩型稀有金属矿区伟晶岩体中石英白云母层出现了三种不同类型的弧形起伏,这些弧形形态仅用矿物的定向生长是难以解释的。弧形石英白云母层具有统一的"背地性"指向(弧形凸起顶端一律朝上)并且越靠近伟晶岩侵入体的顶部弧形凸起越明显,在侵入体侧部边界的石英白云母层不存在弧形凸起形态。这些形态特点与浮力作用下形成的形态具有可比性,暗示浮力与弧形石英白云母层间存在密切的成因联系。石英白云母层与石英钠长石层的间隔出现指示伟晶岩浆中挥发分含量的周期性增加。挥发分含量的周期性增加导致了挥发分不断加入未固结的剩余岩浆中并向伟晶岩体顶部上升,逐步在伟晶岩侵入体的顶部形成了弧形石英白云母层。弧形石英白云母层的大量出现不仅说明伟晶岩侵入体规模较大,也暗示存在有利的挥发分保存环境,对伟晶岩型稀有金属矿产的形成和稀有金属找矿预测起到非常重要的作用。  相似文献