红水河中游地区地质构造稳定性的遥感图像分析

红水河中游地区是以北西向和北东向断裂相交叉为基本构造格局。在新构造运动时期,这两组老构造分段复活,将该区分割成一个相对独立的活动块体。 遥感信息与岩相古地理及汞矿化带相结合的分析结果表明:发震的垭都—紫云深大断裂,在新构造运动时期并未进入断块。遥感信息与历史震中的时空分布和断块结合分析表明:中强震震中绝大多数分布在断块以外,并以右江断裂带以南的频率为最大,由于这里已远在百公里之外,今后若再发生中强震,经过长途衰减,波及坝址的影响有限。 断块内距坝址15—20公里的巴鱼地区,近期发生过4.6级地震。这是一个处在乐业环状构造长轴转折端前沿,也是逻西活动断裂等多组断裂交叉处,小型环状构造也很发育,构造应力容易在此集中,历史震中与小型环状构造同断裂的交叉点关系密切。影像显示该区是相对孤立的局部地段,小震频繁,应力分阶段释放,不具备孕育强震的条件。 龙滩和岩滩电站坝址周围8公里内无大型或活动断裂通过,亦无两组以上断裂交叉点出现,构造稳定性良好,但应注意水库诱发地震的研究。     

Time domain solution for multiple scattering and the coda envelopes

This article summarizes work on multiple scattering based on models of media with randomly distributed scatterers. The scatterers are isotropic and statistically uniform. Measuring distance in terms of mean-free pathL _s and time in terms of the mean-free timesL _s/V, whereV is the velocity of scattered waves, we have more convenient dimensionless distance and time. It can be shown that after the dimensionless time equals 0.65 energy contributed from multiple scattering becomes predominant. Thus the later coda reflects the effect of multiple scattering rather than single scattering. Treating the seismic record, including starting and tail parts, as a whole, the diffusion theory predicts that at a dense distribution of scatterers and a small distance between source and receiver, codas reflect mainly intrinsicQ _i. Of course, this conclusion is coincident with the presumption of the diffusion theory,Q _s>Q _i. However, from a new integral equation of multiple scattering, which deals with the scattered waves and primary waves separately, the conclusion is similar but clearer. This article quotes the new expression for coda energy in two-dimensional space. It shows that if the receiver is close to the source, the coda decay reflects only intrinsicQ _i, then as the distance increases, effects of scatteringQ _s, are involved in the decay feature. The theoretical plots of coda decay show that it seems in most cases in the earthQ _i should not be smaller than one tenth ofQ _s.Project Sponsored by the Joint Earthquake Science Foundation of China.     

A NUMERICAL STUDY OF SHORT-RANGE CLIMATIC OSCILLATION WITH VARIOUS TIME SCALES FORCED BY EL NINO DURING THE NORTHERN SUMMER

The normal mode method is adopted to decompose the differences between simulations with SST(seasurface temperature)anomahes over centra-eastern Pacific and normal SST by use of a nine-layer global spec-tral model in order to investigate short-range climatic oscillation with various time scales forced by ElNino during the northern summer.Investigation shows that El Nino may have the following influence onatmosphere on various space-time scales.Extra-long wave components of Rossby mode forced by convectiveanomaly over equatorial western Pacific resulting from El Nino produce climatic oscillation on monthly(sea-sonal)time scale in middle-high latitudes of Southern and Northern Hemispheres;extra-long wave componentsof Kelvin mode forced by SST anomalies propagate along the equator,resulting in 30—60 day oscillation oftropical and subtropical atmosphere;and its long waves move eastward with westerly,resulting in quasi-biweekoscillation.     

EFFECTS OF THREE-DIMENSIONAL STRUCTURE OF HEATING FIELD ON THE SUMMER MONSOON CIRCULATION IN ASIA

In this paper,a primitive equation linear wave model is used to examine the effects of three-dimen-sional structure of heating field on the behavior of stationary planetary waves in summer and to comparethe roles of different heating functions for the formation and maintenance of summer monsoon circulationin Asia.It is shown that the aloft heating connected with the latent heating,especially the deep condensationheating associated with the cumulus convection in low latitudes,plays a crucial part in the Asian summer mon-soon and the structures of planetary wave responses are quite sensitive to the vertical distribution of heating.     

Electronic Structures of Square Planar Coordinated Transition Metal Ions in Compounds with Gillespite Structure

Electronic structures of square planar coordinated transition metal ions in BaCuSi₄O₁₀ and CaCrSi₄O₁₀ are investigated using the ligand-field theory (LFT), angular overlap model (AOM) and iterative extended Hückel molecular orbital theory (IET). The electronic energy levels of the natural mineral dioptase are also investigated, in which the Cu²⁺ ions occupy the sites of pseudo D_4h symmetry. Both LFT and AOM predict that the crystal-field levels of transition metal ions in these compounds follow such an order that E (²B_1g <E(²B_2g <E(²A_1g )<E(²E_g ), and the frequencies of the crystal-field transitions obtained from point charge calculations are in good agreement with those observed. However, the energy-level order cannot be determined unambiguously from the IET calculation because it depends on the values of parameters chosen for the calculation.     

天然花岗岩块的熔融实验及其岩石学意义

本文详细论述了马兰峪中生代脉状花岗间长岩固体块样品的熔融实验结果,并据此讨论了部分熔融过程中的结构与成份平衡问题。实验表明,最初熔体产生于不同矿物的接触边界上,而且石英—碱性长石之间的熔体量较石英—斜长石间熔体多,而同种矿物之间一般不出现熔体。当熔融程度增高时,两种长石间也开始出现熔体。熔体成分的研究表明,初始部分熔融过程中,局部体系的平衡起着控制作用。     

强震前电磁波异常观测研究

本文报导了1981年以来,特别是1985年以来架设于楚雄观测站的电磁波接收器记录到的电磁波异常现象。后出,1985年一1987年4月停记前,以观测站为中心,400公里为半径范围内,发生了18次M_L>5.0级地震,有15次地震前记录到明显异常(其余3次异常不太明显,当作无异常)。结果表明,电磁波异常观测是一种有希望的临震预报手段。     

The Discovery and Study of Mantle-Derived Dunite Inclusions in Hornblende-Diorite in the Handan-Xingtai Area,Hebei

Phlogopiie-and diopside-bearing dunite occurs as rounded inclusions in hornblende-diorite. Thepetrofabrics, mineral composition and abundances of the trace elements in the dunite indicate that the inclu-sions were derived from the upper mantle and are the residues of high-degree partial melting of mantlepeirdotite. The study of trace elements in the inclusions and their host rocks shows that the magma was origi-nated from the mantle which was enriched in incompatible elements by mantle metasomatism prior to the par-tial melting.     

江西银山矿床岩石稀土地球化学研究

银山矿区的三个旋回火山一次火山岩属同源产物,其原始物质的35%为沉积岩熔体和65%为玄武岩质熔依.是两者的混岩浆.因而.岩石的成因类型属幔壳混合型.根据矿床中蚀变围岩千枚岩的希土组成特征、认为不同矿化蚀变带稀土分配形式基本相似,从而揭示了各带成矿流体成因上的继承性和来源的一致性.