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221.
A Preliminary Study on the Probabilistic Estimation of Deaths from Future Earthquakes in North China
During the period from 1800 to 1989,the degree of fatalities(?from earthquakes in North China(Lat.34.0°-42.0°N,Long.107.5°-125.0°E)varied exponentially with the frequency of earthquake events(N),namely:N=37.71 exp(-0.72?(E-logD,D:deaths).For the periods from 1988 to 1998 and from 1999 to 2009,the probabilities for earthquakes to cause one thousand or more deaths in North China are estimated to be 0.37 and 0.50,respectively,by using the Gumbel's extreme value theory. 相似文献
222.
我国地形与暴雨的若干气候统计分析 总被引:5,自引:3,他引:5
本文以详实的资料,通过对我国不同的地区,不同地形特征的暴雨分析后,得出了地形对暴雨影响的若干气候统计特征。 相似文献
223.
224.
北京西山水平分层剪切流变构造初探 总被引:7,自引:2,他引:7
对比国内外关于变质岩区构造变形序列的实例,可知第一世代的构造变形几乎都以发育不同尺度的强烈扁平化平卧褶皱和有关的轴面流劈理或片理,以及近水平的韧性剪切带等构造组合为特征。北京西山的情况也不例外。这可能代表变质岩区早期构造变形的一种普遍模式,可能是地壳较深构造层次发生大规模透入性水平剪切流变的反映 相似文献
225.
Jiamo Fu Guoying Sheng Deyu Chen Dehan Liu S. C. Brassell A. Gowar G. Eglinton 《中国地球化学学报》1987,6(4):289-296
A preliminary study of newly discovered sphagnum brown coal from the Jingsuo Basin, Yunnan Province, China, which is quite
rich in montan wax, indicates the predominance of highern-alkane homologues and aromatized triterpenoid components. Aromatic hydrocarbons are composed mainly of pentacyclic and tetracyclic
di-, tri- and tetra-aromatic components, which are obviously diagenetically related to higher plant-derived triterpenoids
naturally occurring in the biosphere. Because the sphagnum brown coal still remains in the highly immature stage, it seems
that the progressive diagenetic aromatization of the higher plant-derived triterpenoids may start at a very early stage. 相似文献
226.
Sulphur-containing compounds in sulphur-rich crude oils from hypersaline lake sediments and their geochemical implications 总被引:1,自引:0,他引:1
Guoying Sheng Jiamo Fu S. C. Brassell A. P. Gowar G. Eglinton Jaap S. Sinninghe Damste Jan W. de Leeuw P. A. Schenck 《中国地球化学学报》1987,6(2):115-126
Three sulphur-rich commercial crude oils have been studied, which contain sulphur as high as up to 4–12%. These samples were
collected from Tertiary hypersaline lake sediments of the Jianghan Basin, Hubei Province at different depths, but above the
oil generation threshold (2200m). FPD-GC and GC-MS data show that aromatic fractions of the crude oils are composed of different
homologues of sulphur-containing compounds, including long-chain normal alkyl-thiophenes and-thiolanes, long-chain isoprenoid-thiophenes
and -thiolanes, and benzothiophenes. It is worth noting that the distribution patterns of long-chain alkyl-thiophenes and
-thiolanes from two shallow-seated crude oils are quite similar to those of normal alkanes showing marked even-odd predominance.
It seems that the even-odd predominance of sulphur-containing compounds decreases with increasing burial depth of the crude
oils. The major component of aliphatic fraction is phytane, and similarly the major peaks of aromatic fractions also represent
C20 isoprenoid thiophenes.
Some preliminary conclusions have been drawn from the above discussion: (1) Abundant sulphur-containing compounds may be used
as an indicator of low mature or immature crude oils produced from hypersaline lake sediments; (2) Sulphur-containing compounds
are considered to be early diagenetic products of reactions between elemental sulphur or sulfides and alkanes or their precursors
(phytols, fatty acids, alcohols, etc.), or of bacterial activities, but not direct inputs of organisms. 相似文献
227.
Based on the fluorescence microscopic study, organic compositional analysis and simulating experiments on core samples and
cuttings in the Suqiao area, it is found that the Carboniferous-Permian coal-bearing formations have substrata rich in spore,
cuticle, resin and bark. These substrata have high potential for hydrocarbons, with S1 + S2 high up to about 200, high productivity of liquid hydrocarbons (73.5 mg / g or more) and natural gases (up to 194 ml / g).
The substrata are thought to be an important source for natural gases and condensates found in this area.
According to biomarker compounds and carbon and hydrogen isotope data from the Suqiao natural gas-condensate field, the coal
and its simulating products, characteristics of coal-generated gases and oils from a special kind of coal and their correlation
methods are discussed in the paper.
In terms of the geochemical conditions of formation the distribution regularities of paralic coal rich in hydrogen, the commercial
prospects of Carboniferous-Permian coal-generated oils have been evaluated as well. 相似文献
228.
Based on research on the “Xinyu-type” Sinian iron deposits in Jiangxi Province and metamorphosed iron deposits in Jiangkou and Qidong of Hunan, Sanjiang and Yingyangguan of Guangxi, Longchuan of Guangdong and some other areas in Fujian, the authors have come to the following conclusions:
- The metamorphosed late Precambrian iron ores widespread in south China may be roughly assigned to two ore belts, namely the Yiyang-Xinyu (Jiangxi)-Jiangkou(Hunan)-Sanjiang (Guangxi) ore belt or simply the north ore belt, and the Songzheng(Fujian)-Shicheng (Jiangxi)-Bailing (Longchuan of Guangdong)-Yingyangguan (Guangxi) ore belt or the south ore belt. Tectonically, the former lies along the southern margin of the “Jangnan Old Land”, while the latter along the northwestern border of the “Cathaysian Old Land”.
- Iron deposits of this type occur exclusively in the same interglacial horizon of the Sinian Glaciation in south China. Above and below the ore bed there lie the glacial till-bearing volcanic-sedimentary layers.
- Based on sedimentary features, the iron formations can be divided into four types: silica-iron-basalt formation, silica-iron-clastic rock formation, silica-iron-tuff formation and silica-iron-carbonate rock formation, which progressively grade into each other.
- Iron ores were formed at the late stage of late Proterozoic rifting in neritic environments, with their distribution governed by the rift valleys on the margins of the “Jiangnan Old Land” and “Cathaysian Old Land”. Consequently, intense mafic volcanism as well as weathering and denudation of palaeocontinent during rifting provided material sources for the formation of iron deposits. Meanwhile, warm and humid stationary neritic environment during the south China great glacial period constitutes favorable palaeoclimatologic and palaeogeographic conditions for the deposition of iron ores.
- The iron formations have undergone regional metamorphism of greenschist-amphibolite facies.
229.
230.
七十年代全球地面气温的初步研究(二)——七十年代全球地面气温的变率和主要变率中心影响的传播 总被引:3,自引:0,他引:3
本文计算分析了七十年代全球地面气温变率的时空变化特征。发现全球有三个最大的变率中心:欧亚大陆中部、南极洲和赤道中东太平洋。它们的位置和强度有一定的季节变化。这些区域的温度变化与全球温度的异常有密切的联系,除了直接向周围一定区域扩展外,它们可能以三种主要方式向其它地区传播:(1)纬向温度距平波;(2)经向温度距平波;(3)“经向温度通道”。 因此可以认为,这些地区是全球气候变化的灵敏点,并可能成为异常气候的源地。我国特别是东北地区的温度异常与最大变率中心的温度变化有相当密切的联系。 有意思的是,这三个最大变率中心都位于地球大气的主要热汇区,下垫面热力状况可能是它们形成的一个重要原因。 相似文献