思普地区地震活动和地质构造的相关性研究

红河断裂是云南主要的区域大断裂,区内现代构造运动强烈,但其南段长期无中强地震发生,而离它仅１００ｋｍ的滇西南思普地区地震活动却异常强烈,本在前人工作的基础上,研究了滇西南地区地壳构造和地震活动特点,用人工地震测探等方面的实际资料进一步证实了思普地区存在地较大规模的北东向断层,并提出北东向断层的思普地区地震活动中起重要控制作用的结论。     

山西静乐井水位高值异常及其与华北地震活动的关系

静乐井是山西省地下水观测网中的一口地震观测井。从１９８３￣１９９６年的１４ａ观测中,水位动态变化出现过３个高值时段,水位的高值虽有降雨渗入的影响,但主要可能是反映区域应力场加强的变化过程,因此３个水位高值时段与华北地区中强地震的活跃时期基本吻合。     

南京栖霞山地质环境的开发和保护

地质环境是自然环境的一部分,是人类赖以生存的客观地质实体。地质环境的开发利用,保护与改造,在现实生活中往往是比较突出的矛盾。著名的佛教胜地,风景旅游区和重要的多金属矿产基地的南京栖霞山,在这方面就存在许多问题。对之应采取护岸工程,治水,治支,治坡,保护和改造地质环境,限制地下水的开采量,保持地下水资源的供需平衡等措施,是根治栖霞山地质环境问题的基本对策。     

浅表地质现象对工程建设的影响及其勘探技术

查明浅表部地层地质条件,对多层及高层建筑均至关重要。针对目前上海地区,在运用小螺纹钻孔进行浅表部工程勘察中存在的一些问题,就其如何合理使用,作了若干方面的探讨。     

位移时空综合分析法及其在边坡工程中的应用

以往对监测位移数据分析方法主要是位移-时间关系分析。但监测数据包含了大量对工程设计和施工都很有用的信息,其中不乏位移-空间方面的信息;另一方面,从工程设计和施工角度看,除需要位移-时间信息外,还需要位移-空间信息。位移时空综合分析法的提出旨在综合位移-时间和位移-空间等两方面的信息,为工程设计和施工服务。该方法依表现形式不同又分为竖线法和曲面法两种。本文将通过五强溪船闸边坡工程实例,来进一步说明位移时空综合分析法的原理及其应用。     

The structure of the Baltic Shield region on the basis of DSS and earthquake data

The lithospheric models obtained for the Baltic Shield by using deep seismic soundings are discussed and results from different parts of the shield are compared with models achieved by the investigation of surface waves and of P to S converted waves. The results are found to agree rather well with each other particularly with regard to the first interface (at a depth of 10–15 km) and the whole thickness of the crust (c. 40 km). The macroseismic focal depth determinations of regional earthquakes are correlated with lithospheric structure. The main maximum in the focal depth distributions of Finnish earthquakes occur at a depth of 10–12 km. The geographical distribution of the earthquake epicentres suggests several seismo-active zones in the northern Baltic Shield. One new finding in this field concerns the Lapland zone, which runs in a north-westerly direction.     

Reddening of dune sands—evidence from southeast India

Thin section, SEM, and TEM analyses have indicated that the red ‘teri’ sands of southeast India have formed from weathering in situ of coastal dune sands. The data does not support a detrital origin for the red sands. C¹⁴ dates indicate that dune deposition and weathering, to a maximum depth of 10 m, leading to the formation of a hematite, koalinite and illite rich matrix has taken place rapidly over the past 25,000 years. It is postulated that garnet was a major source of hematite (ferric oxide).     

Mantle heat flow and geotherms for major tectonic units in central Europe

The results of seismic measurements along the deep seismic sounding profile VII and terrestrial heat flow measurements used for construction of heat generation models for the crust in the Paleozoic Platform region, the Sudetic Mountains (Variscan Internides) and the European Precambrian Platform show considerable differences in mantle heat flow and temperatures. At the base of the crust variations from 440–510°C in the models of Precambrian Platform to 700–820°C for the Paleozoic Platform and the Variscan Internides (Sudets) are found. These differences are associated with considerable mantle heat flow variations.The calculated models show mantle heat flow of about 8.4–12.6 mW m^–2 for the Precambrian Platform and 31 mW m^–2 to 40.2 mW m^–2 for Paleozoic orogenic areas. The heat flow contribution originating from crustal radioactivity is almost the same for the different tectonic units (from 33.5 mW m^–2 to 37.6 mW m^–2). Considerable physical differences in the lower crust and upper mantle between the Precambrian Platform and the adjacent areas, produced by lateral temperature variations, could be expected. On the basis of carbon ratio data it can be concluded that the Carboniferous paleogeothermal gradient was much lower in the Precambrian Platform area than in the Paleozoic Platform region.     

Some results of induced polarisation surveys for sulphide mineralisation in parts of Rajasthan and Gujarat,India

Some results of induced polarisation surveys carried out for the exploration of sulphide mineralisation in parts of Rajasthan and Gujarat, employing both frequency-domain and time-domain techniques, are presented. A few typical examples of I.P. results along with borehole sections and results of conventional geophysical surveys have been incorporated. Frequency-domain and time-domain I.P. data have been compared for selected areas.Borehole data pertaining to several areas investigated have corroborated the I.P. results fairly well.     

Velocities of elastic waves andv P/v S ratios in dry and water-saturated rock samples at high pressure

Elastic wave velocities and the ratiov _P/v _S were studied for dry and initially saturated samples of carbonate and crystalline rocks at pressures to 2 kbar. In initially saturated samplesv _P increases in crystalline rock, whereas in sedimentary rock it may either increase or decrease with increasing pressure. Under the same conditionsv _S remains approximately constant in crystalline rocks and decreases in sedimentary samples. The ratiov _P/v _S as a function of pressure increases in dry rocks and decreases in saturated ones. Saturated samples always have higherv _P/v _S ratios than dry ones. It appears that the geometry of the pore space influences the acoustic properties of saturated crystalline rocks.