中国东部第四纪自然环境演化及庐山“冰碛层”堆积时期的自然环境研究   总被引：10，自引：2，他引：8  

黄培华  陆仲家  任振纪  朱凤冠 《地理学报》1987,(4)

根据第四纪地层内孢粉组合和动物群等新资料恢复了我国东部各大区域第四纪各个时期的自然环境特征,其温暖期与干冷期的交替与深海沉积O~(18)温度变化趋势大致对应。庐山三次“冰期冰碛层”内孢粉组合表明均为温暖湿润针阔叶混交林景观,而不是寒冷的冰川环境。  相似文献   

1979年夏季青藏高原大气热量水平输送的周期振荡事实     

陈万隆  刘玉英 《南京气象学院学报》1991,14(2):226-233

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Application of stress release models to historical earthquakes from North China   总被引：5，自引：0，他引：5  

Xiao-Gu Zheng  David Vere-Jones 《Pure and Applied Geophysics》1991,135(4):559-576

Univariate and multivariate stress release models are fitted to historical earthquake data from North China. It is shown that a better fit is obtained by treating separately the Eastern part of the region, including the North China Plain and Bohai Sea, and the Western part of the region, including the Ordos Plateau and its Eastern boundary. Further improvement is obtained by fitting the large events (M7.6) and smaller events in the Western region by different stress release models. The comparisons are made by computing the likelihoods of the fitted models and discounting the number of parameters used by Akaike's AIC criterion. The models are used to develop long-term risk scenarios for the East and West regions.  相似文献   

TL dating of loess in China     

黄宝林  卢良才 《中国地球化学学报》1991,10(3):257-265

TL ages of 56 loess samples collected from Xinjiang and the middle reaches of the Yellow River were determined by using fine-grained quartz and man-made light source bleaching techniques.The results indicate that :1.The well-preserved loess sections in Xinjiang began depositing 400000 a ago.The loess/paleosol series may be comparable with that observed in the middle reaches of the Yellow River but the depositing time was probably delayed by 30000-50000a.2.The bottom boundary age of the Malan loess varies from one place to another.The TL dates can be divided into two group:70000-130000 a and 30000-50000 a.The TL data are con-sistent with the appearance of two warmer climate periods since the Pleistocene,indicating obvious regional differences in stratigraphic development of loess,i.e.,paleosol occurred in the warm climate period in the same location,but loess was deposited in other locations.The initial age of loess deposition tends to become older from west to east and from south to north .In contrast ,the cold cli-matic belt showed an opposite trend.The TL ages of loess provide strong evidence for the Quaternary stratigraphy throughout geological times and the shift tendency of climatic belt.3.The depositing rate of the Malan loess along the middle reaches of the Yellow River varies from place to place but the TL age shows a linear relationship with the depositing thickness.The de-positing rate of loess in the north is higher than that in the south,suggesting that loess materials are derived from desert areas of northern China.  相似文献   

Cosmological implications of BL Lac objects     

G. Z. Xie  F. K. Liu  Y. Y. Zhu  J. H. Fan  R. W. Lu 《Astrophysics and Space Science》1991,179(2):321-329

It has become clear in recent years that relativistic beaming is a good explanation for the BL Lac phenomenon. Of studies based on the relativistic beaming model of BL Lac objects, we note that the orientation of jet's axis to the line-of-sight is very small and, therefore, the observed flux emitted from a rapidly moving source is orders of magnitude higher than the flux in its rest-frame:F _obs = ^{3 +} F _intr, where is the bulk relativistic Doppler factor. Then the observed apparent magnitudem _v must be corrected for this effect. For our 39 samples, the corrected apparent magnitudem _v ^corr and logZ have a good correlation.  相似文献   

Neutrino mass,luminosity variation,and spectrum of SN1987A     

Gang Zhao  Yonggheng Zhao  Jtasheng Huang  Lonlong Feng  Keliang Huang  Qiuhe Peng  Tan Lu 《Astrophysics and Space Science》1988,141(1):169-176

In this paper, the neutrino mass has been determined from SN1987a observation in a manner that the simultaneity of neutrino emission is not regarded as the starting point, but is itself defined through the analysis by Monte-Carlo simulation. The result is that the neutrino mass lies in 3–4 eV, possiblym _v 3.6 eV. Neutrino luminosity variation and neutrino spectrum are also obtained. Comparison with theories gives further support to the mass determination, and also predicts the mass of progenitor star of SN1987a to be in the range of 12–25M .The project supported by the National Natural Science Foundation of China.  相似文献   

The distribution of QSO absorption lines and its implications     

Li-Zhi Fang  Yaoquan Chu  Xingfen Zhu 《Astrophysics and Space Science》1988,149(2):293-299

The distribution of L absorption lines has been investigated in the fractal scheme. It is found that (1) the L absorption clouds distribute completely different from that of galaxies; (2) the L absorption clouds are anti-associated with galaxies and quasars. These results may imply that there are two kinds of objects formed by different processes of clustering. This is favourable for the cosmic-string theory on the formation of large-scale structure of the Universe. In the string model, the objects can be divided into two kinds according to their clustering with or without string loops as their initial density perturbation.On leave from the Center of Astrophysics, University of Science and Technology of China, Hefei, P.R. China. Y. Chu is a research fellow of Alexander von Humboldt-Foundation.  相似文献   

Monochromatic images in stokes parameters and the structure of magnetic fields in sunspots     

Ye Shi-Hui  Jin Jie-Hai 《Solar physics》1986,104(2):273-285

Taking into account magneto-optical effects, we have obtained numerical solutions of the transfer equations for the Stokes parameters, calculated the linearly polarized intensity (U) and constructed its monochromatic images of unipolar sunspots. By comparison with the observational material of the vector magnetograph of the Marshall Space Flight Center, Huntsville (Alabama), we have found that the model of radial magnetic fields may give rise to U monochromatic images close to those observed. The same conclusion has been obtained previously by Landi Degl'Innocenti (1979), although his analysis was performed with the Milne-Eddington approximation instead of a detailed sunspot model. Moreover, we have shown that the model of spiral magnetic fields leads to results in contrast with observations.  相似文献   

Timing of the Nihewan formation and faunas   总被引：2，自引：0，他引：2  

Chenglong Deng  Rixiang Zhu  Rui Zhang  Hong Ao  Yongxin Pan 《Quaternary Research》2008,69(1):77-90

Magnetostratigraphic dating of the fluvio-lacustrine sequence in the Nihewan Basin, North China, has permitted the precise timing of the basin infilling and associated Nihewan mammalian faunas. The combined evidence of new paleomagnetic findings from the Hongya and Huabaogou sections of the eastern Nihewan Basin and previously published magnetochronological data suggests that the Nihewan Formation records the tectono-sedimentary processes of the Plio-Pleistocene Nihewan Basin and that the Nihewan faunas can be placed between the Matuyama-Brunhes geomagnetic reversal and the onset of the Olduvai subchron (0.78-1.95 Ma). The onset and termination of the basin deposition occurred just prior to the Gauss-Matuyama geomagnetic reversal and during the period from the last interglaciation to the late last glaciation, respectively, suggesting that the Nihewan Formation is of Late Pliocene to late Pleistocene age. The Nihewan faunas, comprising a series of mammalian faunas (such as Maliang, Donggutuo, Xiaochangliang, Banshan, Majuangou, Huabaogou, Xiashagou, Danangou and Dongyaozitou), are suggested to span a time range of about 0.8-2.0 Ma. The combination of our new and previously published magnetostratigraphy has significantly refined the chronology of the terrestrial Nihewan Formation and faunas.  相似文献   

太湖平原西北部全新世古河道沉积特征及环境演变   总被引：1，自引：0，他引：1  

舒军武  王伟铭  陈晔 《地层学杂志》2008,32(2):146-152

粒度、磁化率定量数据分析在判明第四系沉积物的来源、识别沉积分异作用、解译古沉积相和环境方面有着重要作用。对太湖平原西北部卜弋桥ZK01钻孔上部全新统如东组进行了粒度和磁化率测试分析,结合该孔孢粉成果,揭示研究区全新世古河道沉积环境和气候明显经历了3个阶段:1)11000—9500cal.aBP,沉积物主要由粉砂组成,粒度证据表明水动力条件较强,孢粉证据显示该阶段气候较温暖湿润;2)9500—3900cal.aBP,沉积物砂组分含量大幅增加,粒度资料显示古河道水动力明显增强,孢粉植被表明该时期处于全新世大暖期,气候暖湿稳定;3)3900cal.aBP以来,粉砂组分在沉积物中占优势,粒度结果表明该阶段水动力显著减弱,孢粉资料和磁化率证据表明研究区自该阶段特别是后期以来逐步出现了明显的人类活动迹象。  相似文献