共查询到20条相似文献，搜索用时 31 毫秒
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人地系统学（Geo-Strategics）及其启示 总被引：2，自引：0，他引：2
人地系统学的概念及其由来 为了系统地探讨科学技术的远期未来及其潜在社会影响，着眼于识别出现的驱动变化的因子，识别可能的影响变化和在未来10～25年产生最大经济、环境和社会效益的科学研究和技术发展领域，加拿大政府实施了跨部门科学技术展望实验项目(STFPP)。 相似文献
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赣南矽卡岩型白钨银矿地质特征及其找矿方向 总被引：1，自引：0，他引：1
赣南矽卡岩型白钨矿床常常共、伴生着独立的银铅锌多金属矿床,综合研究该类型银矿的地质特征、控矿因素等银成矿问题,探索区内银矿的找矿及白钨矿矿山的综合评价工作将有利于改善区内钨锡矿山所面临的形势. 相似文献
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T. Rikitake Dr. 《GeoJournal》1980,4(2):145-152
Present status of earthquake prediction and warning is reviewed with special emphasis on the Large-Scale Earthquake Countermeasures Act in Japan. Following possible regionalization of occurrences of a great earthquake by means of historical data analysis and crustal strain monitoring, statistics of earthquake precursors are presented along with the nature of precursors of various disciplines.The precursor time of the first-kind precursor depends on the magnitude of the main shock. The larger the magnitude is, the longer is the precursor time. The precursor of the second kind has a precursor time amounting to about a few hours, while that for the third kind ranges from a few to several ten days. A practical approach to actual prediction is suggested on the basis of the analysis of precursors. Difficulties in converting a prediction to a warning is briefly pointed out as well. 相似文献
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After World War II Saudi Arabia has experienced spectacular changes. Based on huge oil and gas revenues a particularly rapid
growth of population and a spectacular urbanization took place. One of the most booming cities in the desert environment of
the arabian peninsula is the Kingdoms capital city of Riyadh. With a built-up area of 3.5 km2 only before 1950 the city's present-day expansion reaches more than 500 km2. During the same period of time the population of Riyadh grew from less than 50,000 in 1945 to more than 1.4 Mio. in 1985.
Such an explosive development can be documented best by a satellite image. In this paper the process of urbanization of Riyadh
is presented by the interpretation of a MOMS image taken in 1984, documenting the geographic situation, urban structures,
and the city's development. 相似文献
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A. Zaporozec Dr. 《GeoJournal》1981,5(5):457-471
Everybody wants clean water for drinking, bathing and other domestic uses, but not everybody appreciates the fact that our
own actions are often the worst enemy in achieving that goal. Ground water is one of the most misused and misunderstood resources.
Because ground water and its movement, and consequently also its pollution, is hidden from view beneath the land surface,
the seriousness of ground-water pollution problems has not been recognized until recently.
The sources of ground-water pollution are many and varied because in addition to natural processes practically every type
of facility or structure installed by man and each and every one of his activities may eventually contribute to ground-water
quality problems. The quality of ground water is most commonly affected by waste disposal. Other major sources result from
agricultural activities and ground-water development. In addition to these three major categories, there are other potential
sources of pollution, such as mining, spills, leakage from underground pipes and tanks, and road salting.
All of these activities can generate pollutants which eventually may enter the ground-water systems and slowly begin to move
through the subsurface environment. Once under the ground, the pollutants are hidden from view and the existence of ground-water
pollution becomes evident only if they reemerge on the surface or in water wells. When this occurs, it is almost too late
to do anything about it. The effects of pollution may remain in the aquifers for years, decades, or centuries, because the
residence time (turnover) of ground water is very slow. Ground-water pollution may even result in aquifers or parts of quifers
being damaged beyond repair. 相似文献
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成矿作用研究表明 ,在地球的演化历史中 ,成矿数量有从少到多 ,聚矿能力有由弱到强的演化趋势。中生代为全球规模的成矿大爆发阶段 ,究其原因可能与地球的发展演化密切相关。地球形成的早期 ,由于地球物质尚未充分分异 ,成矿强度不大。当然 ,有部分在地球演化早期形成的矿床 ,在后来的多次构造改造过程中被改造迁移 ,甚至消失。中生代地球进入了一个强烈的地幔热柱活动时期 ,聚集于D”层及外核的成矿物质可通过地幔热柱多级演化向上迁移 ,并在幔枝构造的有利构造扩容带中成矿 ,幔枝构造则成为中生代主要的成矿控矿构造类型 相似文献
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本文通过计算不同构造环境的原生玄武岩岩浆密度,首次提出了两种原生玄武岩浆密度类型:岛弧玄武岩浆(AB)密度类型(Ⅰ);WB MORB岩浆密度类型(Ⅱ)。指出Ⅰ型岩浆密度受控于岩浆起源的fO2和fH2O条件;Ⅱ型岩浆密度则与岩浆起源压力有关。原生岩浆密度可作为判定岩浆产出的地球动力学背景的重要标志之一。考察岩浆密度与压力的关系,指出原生玄武岩浆密度在一定程度上控制了岩浆房的发育部位(深度),制约了岩浆结晶的温压条件,并对岩浆侵位与喷发产生重要影响。在岛弧地区,岩浆密度与地壳厚度变化严格地控制着岛弧岩石系列(Tb-CA-Sh)的时空演变,决定了岩浆的演化途径和结晶条件。利用岩浆密度资料,反演并建立了义敦岛弧区的地壳双层结构模式。 相似文献
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Botryoidal aragonite and its diagenesis 总被引：1，自引：0，他引：1
DJAFAR M. AISSAOUI 《Sedimentology》1985,32(3):345-361
Botryoidal aragonite is a spectacular growth-form occurring as mamelons, up to 100 mm in diameter. Three examples of this particular carbonate cement have been discovered in two distinct areas: in New Caledonia, small-scale mamelons have been recognized within Pleistocene reefal terraces at Ouvea, an Island of the Loyalty archipelago, and in the Red Sea, large-scale mamelons of botryoidal aragonite exist within Pleistocene reefal terraces along the Um Gheig region of the Egyptian Coast. In addition, a similar botryoidal cement, partly dolomitized but exhibiting aragonite relics, occurs within a Miocene reef in the same region. Mamelons of botryoidal aragonite are isolated and/or coalescent but grow only on fixed substrates. They occur within cavities of varied origin. Their fabrics are characterized by fans of elongate euhedral crystals of aragonite fibres. Botryoidal aragonite can be preceded or followed by other types of cements or internal sediment. Despite similar mineralogy, petrography and ultrastructure, there are differences between the fabrics of the Pleistocene botryoids from the Red Sea and Ouvea and the Miocene botryoids from the Red Sea. The former are of submarine origin as confirmed by the strontium content (8500–10,500 ppm) and isotopic composition (δ18O between -0.10 and +0.19% PDB). The latter, related to a Miocene karst, are rich in strontium (average 13,600 ppm), and have an isotopic composition (average δ18O -10.50% PDB) indicative of non-marine precipitation. Diagenesis of these botryoidal aragonites consists of slight dissolution for Pleistocene botryoids and mineralogical transformation for the Miocene botryoids. The latter exhibit the diagenetic sequence aragonite → calcite → dolomite. The aragonite to calcite transformation is a dissolution-reprecipitation process, the void distribution and size influencing the distribution and the size of the replacement calcite crystals. 相似文献
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介绍了用于大口径钻探的ＤＣ型无簧式双作用液动冲击器的结构和工作原理及设计计算结果，给出了其冲程，上阀程和上阀自由行程，下阀程和下阀自由行程的测量及调整方法。 相似文献
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Z. Aizenshtat 《Geochimica et cosmochimica acta》1973,37(3):559-567
Perylene was found in a variety of marine sediments, in a shale and in peat. It is suggested that its precursors arise predominantly from land organisms and are carried into oceanic traps along with detrital minerals. When rates of deposition are fast, and reducing conditions are established within the sediment, biogenic pigment precursors of perylene are converted to the polycyclic aromatic hydrocarbon, which is then stabilized by π-bonding with metals and protected from degradation. 相似文献
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岩溶生态系统是受岩溶环境制约的生态系统,是脆弱的生态系统,缺水、少土、富钙是岩溶生态系统无机环境的基本特征,植物与岩溶环境长期的相互作用,演化出独特的岩溶植物。岩溶植物具有喜钙性、石生性、旱生性,其多样性表现为少属科、寡种属和特有种,更有岩溶生态系统中特有的洞穴弱光带、天坑植物群落。植物是生态系统的生产者,肩负着生态系统的生产力、生态服务功能的重任,退化岩溶生态系统的修复,需要根据中国岩溶生态系统发育特色,探索发展具有仿自然特色的生态产业,走出岩溶区“绿水青山就是金山银山”的道路,完善中国岩溶生态系统理论。 相似文献
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Scientists of different schools and scientific disciplines have for a long time objected to the use of the term 'Anthropogene' as a substitute for 'Quaternary'. The author of this article believes that from positions of modern science their objections are no longer valid. Discussed are new concepts on the duration of the Anthropogene and principles of its subdivision. The study of the interaction of natural environment and its changes with the development of prehistoric man and society is considered to be the major problem of the Anthropogene. 相似文献
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《Geoforum》2017
This paper critically synthesizes empirics and issues in discrete inter-disciplinary literatures to identify ‘open innovation’ as part of an emergent regime of accumulation, overlaying and co-existing with flexible production, and encompassing novel firm-level strategies, new forms of corporate networks, and a disturbing capital-labor relation that informalizes innovative work while cultivating entrepreneurial but self-exploiting subjects. I explain the novelty of open innovation, its genealogy, and the implications for people and conditions of work as much as for firms in a new topology of power relations. I cast the ensemble of strategies and tactics encompassed in open innovation as contingent, continually unfolding, and sometimes chaotic if not destructive for both firms and labor, in contrast to the celebratory tone in the business as well as geography and regional studies literatures regarding its benefits for competitiveness, innovativeness, value capture, and development. Open innovation – the externalization of innovation – entails long-run approaches to innovation and investment that are fraught with problems, prompting the development of short-term tactics to engage the challenges. One short-run strategy, crowdsourcing, bypasses the conventional web of inter-firm relations to connect digitally with individuals of the global crowd, enabling firms to reap the benefits of the crowd’s innovative talents, often without remuneration under circumstances that institutionalize informal work. These neoliberal subjects are best understood in terms of multiple subjectivities. I close by connecting the crowdsourcing of innovative with non-innovative work, both of which are parts of the emergent regime associated with new hiring and work practices that usher in new modes of exploitation. 相似文献
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