山西地区的地壳应力场   总被引：4，自引：1，他引：4  

刘巍  赵新平 《山西地震》1993,(3):3-11

根据近20年山西地区的震源机制结果,得出了山西地壳应力场存在着有别于华北应力场的局部小区域应力场,这种小区域应力场在中部断陷盆地都是以北西—北北西向的水平拉张作用为主,而在东、西两侧隆起区则是以水平挤压作用为主的结论.但如果把上述断层面解中的所有P轴、T轴再分别投影到吴尔夫网上,得到是一个一致性很好的断层面解,由此推断山西地区的平均应力场的主要特征与华北应力场的基本特征完全相同,而山西局部小区域应力场的特征随之消失.  相似文献   

染料交换荧光分光光度法测定地球化学样品中痕量铊     

卢荫庥  安荣战 《岩矿测试》1993,12(4):251-254

研究表明，在Ｈ３ＰＯ４介质中，丁基罗丹明Ｂ可从乙酸异戊酯有机相中的［Ｔ１Ｂｒ４］＾－－结晶紫缔合物中置换结晶紫而形成新的离子缔合三元荧光络合物。详细考察了该络合物形成的最佳条件、荧光特征及萃取溶剂等，制定了地球化学样品中痕量Ｔ１的荧光光度测定新方法，其检出限０．００５μｇ／ｍｌ．Ｔ１量在０－０．５μｇ／ｍｌ范围与荧光强度呈正比。测定了含Ｔ１量０．６１－１．９μｇ／ｇ的８个一级地球化学标样，结果相符  相似文献   

Exploring nonlinear characteristics in seismogenic process     

Zhen-Wen An  Lin-Ying Wang  Yao Chen  Han-Meng Pan 《地震学报(英文版)》1993,6(4):923-930

Power spectral characteristics of the seismic activities before and after the seven large earthquake — Haicheng, Tangshan, Lancang, Longling, Mabian, Puer and Songpan are studied by spectrum analysis method. The results show that they all have continuous power spectrum and aperiodic behaviour. When the time away from the large earthquake occurrence, the characteristics of the seismic activities are obviously accompanied by stochastic components. About one year before main shock, the moving orbits constructed by spectrum amplitudes showed the contracting tendency. And the properties during that time may display as flicker noise. One’s another time almost mixed whole phase space. But the essence of seismic activities after main shocks is a chaotic state accompanied with much noises. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 276–281, 1993. This subject is supported by the Chinese Joint Seismological Foundation.  相似文献   

甘青文化区新石器文化的时空变化 和可能的环境动力^*   总被引：2，自引：1，他引：2       下载免费PDF全文

安成邦  王琳  吉笃学  陈发虎  王鹏 《第四纪研究》2006,26(6):923-927

气候变化引起的环境系统的变动,可以对史前文化的时空分布产生决定性的影响。甘青文化区是我国古文明发祥地之一。这里新石器文化非常发达,遗址丰富,类型齐全,为一个自成体系的古文化中心。通过分析不同类型的新石器文化的时空分布的变化,发现自大地湾文化至马家窑文化时期,研究区文化在空间上扩张,而后逐步向南退缩。这一变化和气候的干湿状况的变化密切相关。5kaB.P.气候逐步趋向干旱,导致文化分布上的空间差异,至齐家文化时期,研究区105°E以西遗址点的空间分布大大地向南收缩,而105°E以东齐家文化的分布范围和仰韶文化基本一致。  相似文献   

四川省气象灾害防御对策初探     

游泳  安亚平  姚志国 《高原山地气象研究》2006,26(3)

根据四川省气象灾害多发、频发的特点,提出四川省气象灾害防御的主要措施和对策,探讨了有关气象灾害防御的保障措施.  相似文献   

An 8.1Ma calcite record of Asian summer monsoon evolution on the Chinese central Loess Plateau   总被引：5，自引：0，他引：5  

Chen XiuLing  Fang XiaoMin  An ZhiSheng  Han WenXia  Wang Xin  Bai Yan  Hong Ye 《中国科学D辑(英文版)》2007,50(3):392-403

Carbonates in loess-red clay sequences consist mainly of calcite and dolomite. The EDTA analysis of carbonates in different size fractions and magnetic susceptibility reveal that calcite is a sensitive index of summer monsoon. The chemical analysis of carbonates and calcite from an 8.1 Ma loess-red clay sequence at Chaona on the Chinese central Loess Plateau shows that the evolution of the Asian summer monsoon experienced four stages, namely 8.1―5.5 Ma, 5.5―2.8 Ma, 2.8―1.5 Ma and 1.5―0 Ma, with increasing intensification and fluctuation, suggesting a possible combining impacts of uplift of the Tibetan Plateau and global changes on the Asian summer monsoon.  相似文献   

Mineral Components, Texture, and Forming Conditions of Hydrothermal Chimney on the East Pacific Rise at 9°-10°N   总被引：1，自引：0，他引：1  

郑建斌  曹志敏安伟 《中国地质大学学报(英文版)》2007,18(2):28-134

To characterize the hydrothermal processes of East Pacific rise at 9°-10°N, sulfide mineral compositions, textural, and geochemical features of chimney ores were studied using ore microscope,scanning electron microscope, X-ray diffraction analysis, and electron microprobe techniques. Results show that there are three mineral assemblages for the hydrothermal chimney ores, namely：（i） anhydrite ＋ marcasite ＋ pyrite, （ii） pyrite ＋ sphalerite ＋ chalcopyrite, and （iii） chalcopyrite ＋ bornite ＋ digenite ＋ covellite. Mineral assemblages, zonational features, and geochemical characteristics of the ore minerals indicate that ore fluid temperature changed from low to high then to low with a maximum temperature up to 400 ℃. The chimney is a typical black smoker. The initial structure of the chimney was formed by the precipitation of anhydrites, and later the sulfides began to precipitate in the inner wall.  相似文献   

南昌市城区暴雨积水的数值模拟     

黎健  殷剑敏  张瑛  蔡哲  单九生  辜晓青  肖安 《南京气象学院学报》2007,30(4):450-456

论述了南昌市城市暴雨积水仿真系统的数学原理和开发成果,并应用实况降水对该系统的模拟精度进行测试。结果表明:大多数(62.6%)模拟计算结果的绝对误差在10 cm以内,只有极少数(2.4%)实际积水与模拟结果的误差超过30 cm。暴雨积水等级试验结果表明,中度以上暴雨积水地段的预报准确率达98%,轻度积水和无积水地段的预报准确率达92%。总体来看,暴雨积水趋势(等级)预报基本准确,定量(积水深度)预报有误差,平均相对误差为6%,模型的预测结果与实况基本相符。通过人工给定不同强度的雨量来模拟南昌市两个重点积水地段的积水过程,得到结论:当降水强度达到20 mm/h时,开始产生积水,降水强度超过30 mm/h时将产生严重积水;两个积水点因排水条件不一样,退水时间差异较大。排水条件差的地段,中—大雨需要15 h退完,暴雨需要24 h以上才能退完;在不同降水强度和排水条件下,最大积水深度出现的时间有明显区别;在暴雨情况下,绝大部分(76%)积水点的最大积水深度出现在2~3 h内。此外,讨论了模拟误差产生的原因。  相似文献   

Climate extremes in Loess of China coupled with the strength of deep-water formation in the North Atlantic   总被引：1，自引：0，他引：1  

Zhengtang Guo  Tungsheng Liu  Nicolas Fedoroff  Lanying Wei  Zhongli Ding  Naiqin Wu  Huoyuan Lu  Wenying Jiang  Zhisheng An 《Global and Planetary Change》1998,18(3-4)

The loess-paleosol sequences of the last 1.2 Ma in China have recorded two kinds of climate extremes: the strongly developed S4, S5-1 and S5-3 soils (corresponding to the marine δ¹⁸O stages 11, 13, and 15, respectively) as evidence of three episodes of great warmth and two coarse-grained loess units (L9 and L15, corresponding to the marine δ¹⁸O stages 22, 23, 24 and 38, respectively) which indicate severest glacial conditions. The climatic and geographical significance of these events are still unclear, and their cause remains a puzzle.Paleopedological, geochemical and magnetic susceptibility data from three loess sections (Xifeng, Changwu and Weinan) suggest that the S4, S5-1 and S5-3 soils were formed under sub-tropical semi-humid climates with a tentatively estimated mean annual temperature (MAT) of at least 4–6°C higher and a mean annual precipitation (MAP) of 200–300 mm higher than for the present-day, indicating a much strengthened summer monsoon. The annual rainfall was particularly accentuated for the southern-most part of the Loess Plateau, suggesting that the monsoon rain belt (the contact of the monsoonal northward warm-humid air mass with the dry-cold southward one) might have stood at the southern part of the Plateau for a relatively long period each year. The loess units L9 and L15 were deposited under semi-desertic environments with a tentatively estimated MAT and MAP of only about 1.5–3°C and 150–250 mm, indicating a much strengthened winter monsoon, and that the summer monsoon front could rarely penetrate into the Loess Plateau region.Correlation with marine carbon isotope records suggests that these climate extremes have large regional, even global, significance rather than being local phenomena in China. They match the periods with greatest/smallest Atlantic–Pacific δ¹³C gradients, respectively, indicating their relationships with the strength of Deep Water (NADW) production in the North Atlantic. These results suggest that the monsoon climate in the Loess Plateau region was significantly linked with the North Atlantic thermohaline circulation on timescales of 10⁴ years.  相似文献   

Magnetostratigraphy and palaeoclimatic significance of Late Tertiary aeolian sequences in the Chinese Loess Plateau   总被引：11，自引：0，他引：11  

Sun Donghuai  An Zhisheng  J. Shaw  J. Bloemendal  & Sun Youbin 《Geophysical Journal International》1998,134(1):207-212

The aeolian Red Clay sequence in the central part of the Chinese Loess Plateau was investigated in an attempt to obtain magnetostratigraphic and palaeoclimatic records. From the results, we deduce that aeolian dust accumulation and the related East Asia palaeomonsoon system began at least 7.6  Myr ago, and that the Tibetan Plateau had reached a significant elevation by that time. The Late Tertiary palaeoclimatic history of the Red Clay as reflected by magnetic susceptibility is reconstructed for the time period 7.6–2.5  Ma. Increases in aeolian dust accumulation for the last 7.6  Myr appear to have a close relation with the uplift processes of the Tibetan Plateau. The remarkable increase of aeolian dust accumulation beginning at 3.2  Ma appears to reflect the influence of an increasing global ice volume on the East Asian monsoon and aeolian dust accumulation.  相似文献