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121.
《地学前缘(英文版)》2017,8(5):951-960
We report the finding of the Wolitu Pb-Zn deposit in Inner Mongolia, China, through a series of geochemical surveys. The Wolitu area, located in the loess-cover area in the Hure Banner, Tongliao City,Inner Mongolia, and neighboring the Horqin Sandy Land to the north, had no previous history of Pb-Zn mining or record of Pb-Zn mineralization. Our study identified a large Pb-Zn anomaly with potential zones of mineralization by stream sediment survey. Random rock sampling reveals limonitization at sporadic outcrops in the gullies. The high concentrations of Pb in the residual debris provided guidelines to fix the position for exploratory trench. Oxidized concealed orebodies were identified by trenching.Blind orebodies in veins hosted within the structural zone between slates and marbles of the upper Carboniferous Shizuizi Formation and the Permian granite were discovered by drilling. It is computed that the ore reserve may reach up to 540,000 tones with Pb grade of 1.27% and Zn of 1.9%. This case study is an excellent example for identifying potential polymetallic deposits in loess covered terrains using geochemical exploration. 相似文献
122.
Genevieve Simpson 《The Australian geographer》2010,41(3):403-423
Landcare groups in Australia work to increase biodiversity, eliminate invasive species and promote sustainable land-use practices. With the implementation of the Rudd government's ‘Caring for our Country’ policy during 2008–09, financial and organisational resources available to these groups diminished. This paper examines whether the National Landcare Program's initial intentions—that agency support could be provided to ‘kick-start’ the community groups into action with the Landcare groups quickly becoming independent bodies—are ultimately realistic. The results show that the majority of Landcare groups continue to be reliant on government-sourced funding and Landcare facilitators, and that those groups which do not have access to support have reduced their activity levels accordingly. Landcare groups were suffering from a reduced volunteer base, with static or decreasing numbers of participants, an inability to set regular meetings and a lack of volunteers to take up leadership positions. The reliance of Landcare groups on government support suggests that Landcare was an unsuccessful form of state-sponsored community participation, making Landcare groups similar to other volunteer organisations in terms of their functional characteristics and reliance on externally sourced funds. 相似文献
123.
本文简要介绍了天津市排水专项规划编制的必要性、方法、理念及远景展望。希望通过本文,读者能对排水专项规划的编制理念有新的认识和提升,进而对排水规划编制有所帮助。 相似文献
124.
Dennis P. Cox 《Natural Resources Research》1993,2(2):82-91
Quantitative mineral resource assessments used by the United States Geological Survey are based on deposit models. These assessments consist of three parts: (1) selecting appropriate deposit models and delineating on maps areas permissive for each type of deposit; (2) constructing a grade-tonnage model for each deposit model; and (3) estimating the number of undiscovered deposits of each type. In this article, I focus on the estimation of undiscovered deposits using two methods: the deposit density method and the target counting method.In the deposit density method, estimates are made by analogy with well-explored areas that are geologically similar to the study area and that contain a known density of deposits per unit area. The deposit density method is useful for regions where there is little or no data. This method was used to estimate undiscovered low-sulfide gold-quartz vein deposits in Venezuela.Estimates can also be made by counting targets such as mineral occurrences, geophysical or geochemical anomalies, or exploration plays and by assigning to each target a probability that it represents an undiscovered deposit that is a member of the grade-tonnage distribution. This method is useful in areas where detailed geological, geophysical, geochemical, and mineral occurrence data exist. Using this method, porphyry copper-gold deposits were estimated in Puerto Rico. 相似文献
125.
人口、资源、灾害与环境是困扰当代人类的几个重大问题.人口的增长,要求有更多的资源,而资源开发、利用的合理与否,又势必对环境产生有利或有害的影响;环境的改善或恶化,反过来又必然影响到资源的增减.因此,如何处理好它们之间的关系,使资源得到合理的开发和利用,同时又保护或改善环境,形成资源开发利用与环境保护改善之间的良性循环,应当是人类共同奋斗的一个目标. 本文依据一些实际资料论述了上述问题以及地球物理学在解决这些问题中所应起的作用. 相似文献
126.
《Marine Policy》2017
The global aquaculture sector has grown continuously over the past 40 years, though unevenly among countries. Differences in factors such as inputs, climate, management, technology, markets, social environment, and institutions might be reasons for the disparities in growth. This study focuses on institutions, by analyzing the relationship between annual growth in the production of the major aquaculture countries and the quality of their institutions over three decades (1984–2013). Based on an ex-ante set of criteria, seventy-four aquaculture countries from five different regions - Africa, the Americas, Asia, Europe and Oceania - were selected. Annual percentage change in total aquaculture production, in terms of quantity and value, was used as a proxy for sector development. Three indices - governance, corruption, and competitiveness - were used as institutional quality proxies. Empirical results suggest that the aquaculture growth did not significantly correlate with the quality of institutions. By region, Africa had the fastest growth in the aquaculture sector, though from a low base, with 7.35% and 9.28% higher annual percentage change in aquaculture quantity and value respectively, than the Asian region. While, the European region experienced significantly lower annual percentage change in aquaculture quantity, a difference of 3.78% compared to the Asian region. Furthermore, the study found that total aquaculture production was not positively correlated with eco-label certification. The study is concluded by discussing the “aquaculture paradox.” 相似文献
127.
通过理论推导,指出在平行断面法资源/储量估算中,在块段相邻剖面不具有相等对应边的情况下,梯形体公式只是一个近似估算公式,存在着一定的误差。而截面圆锥体公式则是一个精确的通用公式,其使用不受相对面积差大小的限制。因此,在这种情况下,建议放弃使用梯形体公式,而统一使用截面圆锥体公式。 相似文献
128.
M.B. Kufner L. Sepúlveda G. Gavier L. Madoery L. Giraudo 《Journal of Arid Environments》2008,72(12):2159-2167
Using microhistological analysis of faeces, we studied the diets of the wild Chacoan Brown brocket deer (Mazama gouazoubira) and the exotic European hare (Lepus europaeus) by comparing plant species frequency in faeces with plant species availability. Research was conducted in the dry southern portion of South American Chaco, in forests subjected to livestock ranching in the north of Córdoba province, Argentina. The diet of the Brown brocket deer was more closely related to forage availability (C=0.82195) than the diet of the European hare (C=0.38565). Dicots comprised 90% of the Brown brocket deer diet and were preferred throughout the year, while gramineous species were consumed in low amount. In the diet of the European hare, gramineous species were frequent (65 to 87%) and preferred in every season but in winter, when dicots were consumed in higher proportions (92%). Differences in feeding habits and in habitat use would allow both herbivores to coexist; however, probable competition for food with the European hare during the dry period, in addition to habitat loss, threatens survival of the Brown brocket deer. 相似文献
129.
阐述了南海海龟资源状况,研究了海龟的生态习性及其洄游产卵规律,並进行人工孵化、培育稚龟和标志放流的试验,初步达到了资源繁殖保护的目的。 相似文献
130.
拟调和性及重调和性重力场源的正交分解 总被引:1,自引:0,他引:1
文章针对物理大地测量学反问题研究中的拟调和性重力场源及重调和性重力场源,将该研究中的理论核心-正交分解定理予以具体实现。使得这一定理实际应用于场源结构的解释与分析成为。同时,给出并证明几个具有重要实用意义的关于零外部位密度、拟调和性及重调和性场源性质的基本公式。最后对具体实现场源正交分解的实际步骤、正交分解定理的实质、以及物理大地测量学反问题研究中关于场源涵数的主要限制的意义予以评述。 相似文献