第二代航磁黄沙坪异常的分解及其矿产新空间     

蔡家雄 《湖南地质》1990,9(2):1-9

本文采用同时具有识別、分解、解释异常三重作用的三元解释法■,在黄沙坪异常负值区有效地提取了由未知的深源磁性体引起的剩余异常。该异常与已知的中、浅源磁性体分处于极为类同的成矿地质背景中。后者与隐伏岩体、铅锌多金属盲矿体之间有着密切的成生联系。这为前者间接找矿提供了有力的依据。定量解释结果中,两者间的磁矩等效关系,论证了已知矿床西侧深部空间里,仍存在找到又一个大型矿床的前景。  相似文献   

冀北坝上地区深部地质构造特征及其对火山活动和铀成矿的控制作用     

桑吉盛  李利权  田万文  张振强 《铀矿地质》1994,(2)

冀北坝上地区位于华北地台北缘。其深部地质构造有两个显著特征：一是全区性的莫霍面下拗，地壳增厚；二是软流圈部分伸入到下岩石图上部，造成局部地区地幔上隆，地壳减薄。火山喷发形成的沽源火山盆地和大滩火山盆地与两个地幔上隆，地壳减薄区，上下相互对应。铀矿床（点）沿地幔隆起周边构造活动带规律性分布。上述两事实有力地证明了深部地质构造对中新生代火山活动和铀成矿的控制作用。沿地幔隆起周边构造活动带是今后寻找铀及多金属矿产的有利地段。  相似文献   

我国太平洋深海沉积研究综述   总被引：1，自引：0，他引：1  

鹿化煜 《地球科学进展》1994,9(1):20-24

总结了我国对太平洋深海沉积物组成、分布、形成及深海沉积中宇宙尘、海洋沉积通量、铁锰结核的研究成果,指出了在全球变化研究中太平洋深海沉积的研究课题。  相似文献   

Determination of arsenic(III) for the investigation of the microbial oxidation of arsenic(III) to arsenic(V)     

B. Hambsch  B. Raue  H.-J. Brauch 《洁净——土壤、空气、水》1995,23(4):166-172

Recent evaluations of acute and chronical toxicity of arsenic resulted in a reduction of the standard value for total arsenic from 40 μg/L to 10 μg/L in drinking water which will be valid in Germany after a transition period as from January 1996. Arsenic is well known as substance of deep groundwaters, mainly of geogenic origin and normally found as As(III) or As(V). As(V) is well removable by flocculation and filtration after adding iron salts. As(III), however, has to be oxidized first to As(V). Therefore, it is important for treatment techniques to be able to distinguish between As(III) and As(V). A modified determination of As(III) using flow injection analysis was installed and optimized in order to investigate whether As(III) may be oxidized to As(V) by bacteria in natural waters. The results showed that at 4°C, no As(III)-oxidation was observed within 14 days. At room temperature, however, in the bacteria-containing samples, an As(III)-oxidation was found starting after 3 to 7 days. After 14 days, no As(III) was left over. In contrast, in the sterile samples, no As(III)-oxidation could be observed within 14 days. These results demonstrated that microbial processes influence the oxidation of As(III) to As(V) in natural waters.  相似文献   

对胶南群的异议     

纪壮义  赵环金 《地震地质》1995,17(1):79-85

对苏北～胶南一带胶南群的变质岩系进行研究，其边界特征、横向不连续性、岩石类型及相互关系、同位素年龄等资料表明，胶南群不具有单一地层单元的含义，而是挟于五莲－荣成断裂与海州－泗阳断裂之间的构造岩石组合体，它由上壳岩类和深源岩类组成，前者包括了３个构造位。其形成可能与边界深大断裂的开合作用有关  相似文献   

内蒙古阴山地区特异区域重磁场与深部构造   总被引：12，自引：6，他引：12       下载免费PDF全文

王谦身  滕吉文  王光杰  徐亚 《地球物理学报》2005,48(2):314-320

根据内蒙古阴山山系及邻近地区的布格重力异常分布特征，发现阴山、大青山山地和呼包盆地地区的布格重力异常分布与地形高程呈“同步型”的特异变化特征.而该地区航磁异常分布呈现为阴山山区是大面积负磁异常区，呼包盆地为强正磁异常区的特异磁异常分布特征.通过对地震、大地电磁数据、特别是重力数据资料的处理分析，给出阴山山系和呼包盆地地区的地壳结构，均表明地壳底界面都没有明显的下凹与上凸，且盆地北缘为两大块体的接触带.这些特征可能表征着阴山山系和呼包盆地重磁异常呈特异变化的一些原因.  相似文献   

厚松散层钻探工艺技术     

陈娜  朱磊  从常奎 《陕西地质》2007,25(2):66-71

在厚松散层中进行钻孔施工较常规钻孔存在一些技术难题,按照常规方法达不到钻孔目的或者花费较大的人力和物力。本文通过分析松散层钻孔正常钻进的影响因素,采用正循环钻孔施工技术进行施工,提出钻孔防偏和纠偏措施,最后给出了厚松散层钻孔施工技术措施,对厚松散层钻探技术具有一定的指导意义。  相似文献   

Hydraulic properties of the crystalline basement   总被引：1，自引：1，他引：1  

Ingrid Stober  Kurt Bucher 《Hydrogeology Journal》2007,15(2):213-224

Hydraulic tests in boreholes, up to 4.5 km deep, drilled into continental crystalline basement revealed hydraulic conductivity (K) values that range over nine log-units from 10⁻¹³−10⁻⁴ m s⁻¹. However, K values for fractured basement to about 1 km depth are typically restricted to the range from 10⁻⁸ to 10⁻⁶ m s⁻¹. New data from an extended injection test at the KTB research site (part of the Continental Deep Drilling Program in Germany) at 4 km depth provide K=5 10⁻⁸ m s⁻¹. The summarized K-data show a very strong dependence on lithology and on the local deformation history of a particular area. In highly fractured regions, granite tends to be more pervious than gneiss. The fracture porosity is generally saturated with Na–Cl or Ca–Na–Cl type waters with salinities ranging from <1 to >100 g L⁻¹. The basement permeability is well within the conditions for advective fluid and heat transport. Consequently, fluid pressure is hydrostatic and a Darcy flow mechanism is possible to a great depth. Topography-related hydraulic gradients in moderately conductive basement may result in characteristic advective flow rates of up to 100 L a⁻¹ m⁻² and lead to significant advective heat and solute transfer in the upper brittle crust. An erratum to this article can be found at  相似文献   

Learning about learning: lessons from public engagement and deliberation on urban river restoration   总被引：1，自引：0，他引：1  

JUDITH PETTS 《The Geographical journal》2007,173(4):300-311

This paper provides a new discussion of how people learn through deliberative processes, drawing upon empirical analysis of a novel public engagement process for urban river restoration. Such critical evaluation is rare and yet will be crucial to both theoretical development and learning about engagement practice, not least in a policy area subject to strong regulatory drivers for public participation. The analysis supports two important learning mechanisms – the use of 'gatekeepers' of knowledge, interests and values, and the privileging of narrative. It provides new evidence of instrumental and communicative learning about shared priorities and criteria for effective river restoration that evolved through the deliberative process and directly informed the restoration scheme. It is important to question whether and how such site or context-specific learning might inform other restoration schemes. Finally, the paper questions the often ignored issue of expert learning, not least the issue of the link between individual and organizational learning.  相似文献   

Deriving rules from activity diary data: A learning algorithm and results of computer experiments   总被引：1，自引：0，他引：1  

Theo A. Arentze  Frank Hofman  Harry J.P. Timmermans 《Journal of Geographical Systems》2001,3(4):325-346

 Activity-based models consider travel as a derived demand from the activities households need to conduct in space and time. Over the last 15 years, computational or rule-based models of activity scheduling have gained increasing interest in time-geography and transportation research. This paper argues that a lack of techniques for deriving rules from empirical data hinders the further development of rule-based systems in this area. To overcome this problem, this paper develops and tests an algorithm for inductively deriving rules from activity-diary data. The decision table formalism is used to exhaustively represent the theoretically possible decision rules that individuals may use in sequencing a given set of activities. Actual activity patterns of individuals are supplied to the system as examples. In an incremental learning process, the system progressively improves on the selection of rules used for reproducing the examples. Computer experiments based on simulated data are performed to fine-tune rule selection and rule value update functions. The results suggest that the system is effective and fairly robust for parameter settings. It is concluded, therefore, that the proposed approach opens up possibilities to derive empirically tested rule-based models of activity scheduling. Follow-up research will be concerned with testing the system on empirical data. Received: 31 January 2001 / Accepted: 13 September 2001  相似文献