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1.
A new natural,super-hard,transparent polymorph of carbon from the Popigai impact crater,Russia 总被引：1，自引：0，他引：1
Ahmed El Goresy Leonid S Dubrovinsky Philippe Gillet Smail Mostefaoui Günther Graup Michael Drakopoulos Alexandre S Simionovici Varghese Swamy Victor L Masaitis 《Comptes Rendus Geoscience》2003,335(12):889-898
A natural shockwave event led to the formation of a new crystalline polymorph of carbon in gneisses from the Popigai crater, Russia. The new species occupies the interior of a multiphase assemblage and is entirely enveloped by lonsdaleite and graphite. Polishing hardness of this new phase is greater than that of lonsdaleite. Micro-beam synchrotron X-ray diffraction, imaging and fluorescence studies revealed a pure transparent carbon phase. The diffraction pattern is indexed in terms of a cubic cell (a=14.697 Å, space group Pm3m.). This species was neither encountered in static or dynamic high-pressure experiment nor predicted by theoretical calculations. To cite this article: A. El Goresy et al., C. R. Geoscience 335 (2003). 相似文献
2.
John L. Berkley G.Jeffrey Taylor Klaus Keil George E. Harlow Martin Prinz 《Geochimica et cosmochimica acta》1980,44(10):1579-1597
Ureilites are carbon-bearing olivine-pigeonite achondrites which constitute a unique achondrite type. We performed a comprehensive mineralogical and petrological study on eight ureilites (Kenna, Novo Urei, Goalpara, Haverö, Dingo Pup Donga, Dyalpur, North Haig, and ALHA77257) the results of which were used to construct a hypothesis for the origin of ureilites. This hypothesis suggests that ureilites are primarily olivine-pigeonite cumulates which crystallized from a silicate liquid that also contained suspended solid carbon phases, mainly graphite. This carbon caused reduction of the melt and influenced ureilite mineral compositions. Carbonaceous material was trapped by settling cumulus mafic silicates along with other intercumulus material to form the carbon-rich ‘veins’ common to ureilites. Petrofabric analyses show that mafic silicates are oriented in lineated and foliated patterns characteristic of cumulate rocks, specifically adcumulates. Strain state of silicates suggests that ureilites were deformed subsequent to lithification by mild tectonic stress as well as by moderate to severe shock. The latter event caused the formation of micron-sized diamonds and lonsdaleite from graphite and carbon-induced reduction of silicate grain margins during temporal shock-heating. 相似文献
3.
Everett K. Gibson Jr. 《Geochimica et cosmochimica acta》1976,40(12):1459-1464
Abundances of carbon and sulfur in the Kenna ureilite are 2.219 ± 0.060 wt. % C and 0.179 ± 0.008 wt. % S. Secondary carbonates resulting from terrestrial weathering account for 0.25 ± 0.02 wt. % C. No hydrocarbons were detected during gas release measurements. Most of the carbon is in graphite, diamond, or lonsdaleite. The sample of Kenna contained 0.95 ± 0.05 wt. % H2O. Total carbon and sulfur measurements were made on three additional ureilites: Haverö, Dingo Pup Donga, and North Haig. Ureilite carbon abundances are similar to those of C-2 chondrites, whereas sulfur abundances are a factor of 10 less than C-2 chondrites and ordinary chondrites. The elemental abundances, ratios, and phases present in the ureilites rule out a direct genetic relationship between the ureilites and the carbonaceous chondrites. 相似文献
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John L Berkley H.Gassaway Brown Klaus Keil N.L Carter J-C.C Mercier Glenn Huss 《Geochimica et cosmochimica acta》1976,40(12):1429-1437
The Kenna ureilite was found in February, 1972 near the town of Kenna, Roosevelt County, New Mexico U.S.A., weighed 10.9 kg, and measured 26.7 × 14.7 × 14.2 cm; it is the seventh known ureilite. The meteorite is composed of xenoblastic olivine (Fo79.2), commonly rimmed by forsterite (Fo99), and pigeonite (En73Wo9Fs18), in a volumetric ratio of 3:1, set in a matrix of three carbon polymorphs (graphite, lonsdaleite, and diamond) plus nickel-iron metal and troilite. Some thin metalliferous veins penetrating silicate grains contain secondary inclusions of melt with high-calcium clinopyroxene (high-Ca, Mg-rich augite to augite), andesine, K-feldspar, chromite, and siliceous CaO- and alkali-rich glasses of variable compositions.Textural, mineralogical and fabric information suggest a complex history for Kenna, involving igneous, metamorphic and shock processes. The rock appears to have originated as an ultramafic cumulate whose texture and structure was modified by adcumulus processes and by solution and redeposition in a weak deviatoric stress field. A strong mineral elongation lineation was produced during this high-temperature phase accompanied by mild plastic deformation of olivine on the system 0kl[100]. Superimposed on this original texture and fabric are processes resulting from light to moderate (50–250 kbar) shock deformation, as manifested by fracturing of the silicates, slip parallel to (001) in olivine, and twin and translation gliding parallel to (100) in the clinopyroxene. Lonsdaleite and diamond probably formed during this shock phase, which may be associated with the break-up of the parent body, but the relative time of introduction of the carbon-rich matrix is still unresolved. 相似文献
6.
天然闪锌矿可见光催化还原甲基橙的实验研究 总被引：4，自引：0，他引：4
本文研究了可见光下天然闪锌矿的光催化还原能力,通过可见光下天然闪锌矿对甲基橙的光催化降解实验讨论了天然闪锌矿晶格中的杂质缺陷、导带能级位置、光生空穴捕获剂和溶液pH值对可见光催化降解效率的影响。结果表明,在抗坏血酸做空穴捕获剂的条件下,经2 h的可见光催化实验,甲基橙能被天然闪锌矿完全还原降解。天然闪锌矿晶格中丰富的杂质缺陷在禁带中形成杂质能级,可将闪锌矿对光的响应拓展到可见光的波长范围。与天然金红石相比,闪锌矿对甲基橙的较强光催化还原降解效果与其导带电子更负的氧化还原电势有关。此外,空穴捕获剂和pH值的选择都是影响催化效果的关键因素。天然闪锌矿在可见光催化降解污染物领域颇有应用前景。 相似文献
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近年来,我国明确提出“探索编制自然资源资产负债表,对领导干部实行自然资源资产离任审计”。但如何将自然资源资产负债表运用于地方领导干部自然资源离任审计实践,目前仍处于探索阶段。从制度功能角度来看,在地方领导干部自然资源资产离任审计中,自然资源资产负债表通过为领导干部离任审计提供有效的基础信息,减少自然资源管理风险,使自然资源资产离任审计有效约束领导干部任期内自然资源管理工作,充分提高自然资源管理效率。用资产负债表模糊综合评价法对我国典型的干旱、半干旱区水资源短缺的甘肃省2014-2016年内水资源管理与保护的履责情况进行综合评价。结果表明,以自然资源资产负债表为基础的领导干部自然资源离任审计,能够通过自然资源管理责任变动状况的评价指标,深入分析地方政府自然资源管理存在的问题,总体评价领导干部任期内自然资源管理的有效性。 相似文献
9.
天然气的加速式二次运移过程研究 总被引：2，自引：1，他引：1
在静水条件下,游离相天然气运移的主要动力是浮力,阻力是毛细管力。根据前人的实验数据,通过理论计算发现,浮力和毛细管力均受地层温度和压力的影响,气体在储层中上浮的临界高度随地层温度和压力的降低而增大。根据气体状态方程及天然气运移的动力学理论,推导出温度和压力降低前、后气体流速比方程,用其计算了不同储层中临界气体长度并分析不同储层中相同长度的气体在运移途中的变化规律。由此发现,在运载层物性不变的情况下,天然气沿上倾地层向上倾方向运移的过程,是随地层温度和压力不断降低、其运移速度逐渐增大的过程,如果有后续气体的加入,会使气体长度增大,致使运移速度增加得更快。 相似文献
10.
研究与寻找新的油气资源、开拓勘探新领域 总被引：4，自引：0，他引：4
王先彬 《矿物岩石地球化学通报》2002,21(1):22-25
天然气将成为人类第四代能源。非常规天然气资源量比常规天然气的资源量多一个量级以上。研究非常规天然气理论，开拓勘探新领域将为人类提供丰富的天然气资源。中国在非生物成因天然气、深层石油天然气和煤层等非常规天然气研究和勘探方面均取得重要进展，对改变能源结构，满足未来发展对能源的需求将会有重要战略意义。天然气的长距离传输要求储量在1000亿m^3以上，以确保满足生产量为300－500万m^3的输气量，维持30年以上，可获得较大的经济效益和社会效益。 相似文献
11.
Urban expansion has become one of the main factors influencing natural habitats. Understanding the advances on the assessments of the impacts of urban expansion on natural habitats is of great significance to balance the contradiction between urban expansion and natural habitats protection and to improve urban sustainability. Therefore, this paper reviewed the assessments of the impacts of urban expansion on natural habitats. The results showed that the number of papers and the frequency of citations continuously increased. Previous studies mainly evaluated the impacts of urban expansion on natural habitats in broad sense, and emphasized the impacts on the area and spatial patterns of natural habitats. The scale of previous studies concentrated on the local scale, and the spatial statistics were used as the most popular assessment method. Previous studies have laid a good foundation for understanding the impacts of urban expansion on natural habitats, but there are shortcomings in several aspects of contents, scales and methods. To solve those shortcomings, we propose a framework for assessing the impacts of urban expansion on natural habitats based on the principle of "multiple perspectives, multiple scales, and multiple methods". This framework will be helpful to assess the impacts of urbanization on natural habitats in a more effective way. 相似文献
12.
David King 《Natural Hazards》2008,47(3):497-508
The concept of a natural hazard is a human construct. It is the interaction with human communities and settlements that defines
a natural phenomenon as a natural hazard. Thus the end point of hazard mitigation and hazard vulnerability assessment must
involve an attempt to reduce, or mitigate, the impact of the natural hazard on human communities. The responsibility to mitigate
hazard impact falls primarily upon governments and closely connected non-government and private institutional agencies. In
particular, it is most often local government that takes the responsibility for safeguarding its own communities, infrastructure
and people. Hazard vulnerability of specific local communities is best assessed by the local government or council, which
then faces the responsibility to translate that assessment into community education and infrastructural safeguards for hazard
mitigation. This paper illustrates the process of local government engagement in hazard mitigation in Australia, through the
Natural Disaster Risk Management Studies, as a first step towards natural disaster reduction. 相似文献
13.
天然气因其丰富的储量和清洁低碳的属性受到世界各国普遍重视。在未来30~50年内,天然气的消费量和比重还会继续上升,预计在2040年前后将成为第一大能源。科学分析天然气全球供需格局和研判其未来变化,是科学制定中国天然气发展战略的前提和基础。全球天然气的生产和消费严重分离,形成了基本的天然气供需格局。但新世纪以来,天然气领域全球出现了许多重大而影响深远的变化,美国页岩气革命改变了天然气的供应格局,2013年的俄乌争端将改变了天然气的贸易格局,固有的市场体系必不可免地随之改变。中国天然气需求的增速将大大高于产量的增速,天然气供需缺口将不断扩大。本文提出了我国天然气发展的战略思路,对我国天然气需求的供应保障和产业的可持续发展具有重要的理论和实践意义。 相似文献
14.
青藏高原天然气水合物资源预测 总被引：24，自引：8，他引：24
青藏高原分布着中国规模最大的多年冻土带,发育有良好的中、新生代海相地层及海相、陆相盆地,为高原天然气水合物矿藏的形成创造了有利条件。本文根据陆上天然气水合物的形成条件,从多方面讨论了水合物形成的可能性及其矿藏有利的分布位置,认为青藏高原完全有条件形成天然气水合物矿藏,最有利的分布区是藏北地区含油气盆地储集层的露头区。对水合物矿藏的研究不但具有资源意义,而且还有潜在的环境意义。 相似文献
15.
Ⅲ型干酪根烃源岩生气增压定量评价是一个复杂过程, 因为Ⅲ型干酪根以生气为主的同时伴生少量的油生成, 而且在达到一定的温度条件下原油还将逐渐裂解成天然气.在考虑烃源岩生烃过程中天然气的渗漏和排出、氢指数对生烃量的影响、原油裂解成气、生烃作用产生的超压对孔隙水, 油和干酪根的压缩作用、天然气在孔隙水和石油中的溶解作用等因素的基础上建立了Ⅲ型干酪根烃源岩生烃增压定量评价模型, 并对模型参数进行敏感性分析.Ⅲ型干酪根烃源岩生气增压受到烃源岩孔隙度、成熟度、有机质丰度、天然气残留系数等多种参数的影响.有机碳含量、氢指数和天然气残留系数3个参数中以氢指数对Ⅲ型干酪根烃源岩生烃增压产生的影响最大, 天然气残留系数影响最小.天然气残留系数只要大于0.2就可以产生超压, 表明保存条件不是Ⅲ型干酪根烃源岩形成生烃增压最主要的控制因素. 相似文献
16.
生态安全条件下亚洲沙区土地利用结构研究 总被引：7，自引：0，他引：7
基于数字地图与遥感影像资料,通过分析土地利用格局与沙尘传输关系,研究了生态安全条件下土地利用结构优化的模式、方法与技术。研究表明：①亚洲生态安全条件下的土地利用/覆盖宏观三圈格局为: 内圈以自然保护为主的沙漠地带;中圈以建设人工草地为主,辅以大面积自然恢复的草原地带;外圈以农、林、牧复合为主的交错地带。中国处在宏观三圈格局的中东部,北方沙区是影响东亚沙尘暴的重要源区。②中国半干旱沙区土地利用呈现微观三圈模式,基于RS数据,依据“大面积搞生态,小面积搞生产”的原则进行的土地利用结构优化,提出了外圈沙丘地恢复天然草地生态用地——中圈草原地带大面积搞生态—小面积搞牧业生产——内圈甸子地高效农业生产用地的生态—生产范式。③典型区科尔沁沙地土地利用结构优化的成套技术,可为类似地区政府土地利用决策与生态补偿机制提供支持。 相似文献
17.
Natural Gas Types,Distribution Controlling Factors,and Future Exploration in the Western Qaidam Basin 总被引：1，自引：0，他引：1
GUO Zeqing SUN Ping LI Jian ZHANG Lin LIU Weihong TIAN Jixian ZHANG Shaosheng ZENG Xu 《《地质学报》英文版》2014,88(4):1214-1226
The Paleogene and Neogene oil and gas in the western Qaidam basin have a regular distribution in three concentric zones from the edge to the center of the basin.Natural gas mainly occurs in the inner zone,and the gas-oil ratio of the northern area of the basin is significantly higher than that of the southern area.Large amounts of carbon isotope data of natural gas,plotted in Xshaped and comprehensive identification diagrams for the southern area and northern area,respectively,were used to identify the types of natural gas.The large-scale distribution of natural gas is highly consistent with the Ro values of major source rocks,but is poorly correlated with the type of organic matter.This indicates that the main controlling factor of natural gas distribution is organic matter maturity,and the kerogen types act as the basis for the formation of different types of natural gas.Paleouplifts and squeezed anticlines near hydrocarbon generation depression centers,which are major natural gas-rich regions,control the migration directions of natural gas,while hydrocarbon migration pathways and fault systems connecting gas sources are the most important factors for natural gas reservoir formation in the inner basin.Therefore,favorable zones for natural gas distribution can be predicted on the basis of the distribution of thermal evolution and the gas generation intensity of major source rocks as well as the structural map.The Shizigou-YoushashanYingdong-Dawusi,Youquanzi –Kaitemilike- Youdunzi,and Xiaoliangshan – Nanyishan- Dafengshan structural belts are favorable zones for natural gas accumulation.This study has important theoretical and practical significance for future natural gas exploration. 相似文献
18.
发展需要消耗资源,我国资源供给形势严峻。可持续发展是我国经济发展的必然选择,资源持志开发和利用是实现可持续发展的关键。实现这一点,一方面要充分发挥市场机制在资源配置中的基础作用,另一方面要加强对资源开发和利用的宏观调控作用,保证资源的有效供给。 相似文献
19.
Risk evaluation of China’s natural disaster systems: an approach based on triangular fuzzy numbers and stochastic simulation 总被引：6，自引：6，他引：0
To deal effectively with the evaluation problem of natural disaster risk system affected by many uncertain factors, a multivariate
connection number expression is presented. This expression is based on the index samples and evaluation grade criterions of
natural disaster risk system and is capable of describing the hierarchy property and fuzziness of membership relationship
between index samples and evaluation grade criterions. In this proposed method, the fuzzy evaluation grade criterion problem
is resolved by combining triangular fuzzy numbers with multivariate connection number theory, and triangular fuzzy numbers
are used to express the discrepancy degree coefficients of connection number and evaluation index weights. Accordingly, a
connection number-based evaluation method for the natural disaster system of China (named CN-TFN for short) is established
using triangular fuzzy numbers and stochastic simulation. The application results show that the spatial distribution of natural
disaster risk grades of China has the trend of aggrandizement from west to east of China. The economically developed and densely
populated coastal areas are very likely to have a high level of natural disaster risk grade or above; thus, these areas are
the key regions of the natural disaster risk management of China. The results also show that the CN-TFN is able to reflect
practical conditions of the evaluation problem of natural disaster system and to provide more reliability information as compared
to the existing evaluation methods. This is as a result of its comprehensive usage of various information of subjective and
objective uncertainties in the evaluation process of natural disaster risk system and its expression by confidence intervals.
Due to the simplicity and generalization, the CN-TFM is applicable to comprehensive risk grade evaluation of various natural
disaster systems. 相似文献
20.
Forecasting the Conditional Probabilities of Natural Disasters in Canada as a Guide for Disaster Preparedness 总被引：1，自引：1，他引：1
Mohammed H. I. Dore 《Natural Hazards》2003,28(2-3):249-269
A variety of natural disasters occur in Canada. Yet apart from simple ``return period' calculations, no apparent research seems to have made systematic use of the OCIPEP database on all natural disasters in Canada over the period of 1900 to 2000. This paper (a) describes the main characteristics of natural disasters in Canada, and (b) presents a methodology that is a first attempt to use the database to forecast conditional probabilities of each type of natural disaster. The forecast probabilities can then be used to work out the expected social costs of each type of natural disaster. The expected costs in turn suggest what kind of policy priorities are indicated for disaster preparedness. The key results of this methodology are that Hydrometeorological Disasters are increasing over time and of these, the ranking in order of priority for preparedness should be droughts, heat waves, floods and ice storms. 相似文献