Widespread occurrence of aquifers currently undetectable with the MRS technique in the Grenville geological province, Canada

In the summer of 2003, a series of field tests were made over aquifers within or next to the Grenville geological province, Canada. Twelve sites distributed within three general areas of the province and nearby to its southern border were surveyed with the MRS (Magnetic Resonance Sounding) technique. Each site was characterized by saturated shallow water bearing layers of high effective porosity. The tests were planned to evaluate the MRS technology in such environments for groundwater resources quantification and aquifer/aquitard media characterization. A priori, the environmental conditions in Eastern Canada were assumed favorable for MRS work such as low to moderate ambient noise, earth's field value above 55,000 nT, targets consisting of shallow and high porosity aquifers. Despite such conditions, no clear MRS responses were observed. Following supplementary investigations, this is now attributed to the wide-scale occurrence of disseminated magnetite within the aquifers which shorten the signal decay time. Although the lack of MRS response over aquifers has been reported before, this was not the case for such widespread occurrence. This also supports the adaptation of the MRS technology to conditions similar to those observed in the Grenville province.     

遥感岩性识别研究的发展趋势--遥感与航空放射性信息集成

岩石的吸收光谱主要是由杂质、包体、蚀变及替代成分产生的,每种岩石都难以形成象它的组成成分那样具有可分辨的很清晰的光谱特征;不同类型的岩石放射性元素的含量和分布特征是不同的,岩石放射性信息是岩性识别研究的重要判据。遥感与航空放射性信息的集成．既能提取光谱图像中的光语信息和空间纹理信息。又可利用航空放射性信息常常具有的甚至是诊断性的岩性识别能谱标志。能明显提高识别岩性的精度,更重要的是能谱不受值被的影响,有利于识别植被覆盖区的岩性。因此,这可能是遥感岩性识别研究的发展趋势之一。     

新疆玛因鄂博断裂带中花岗质糜棱岩锆石U-Pb SHRIMP和黑云母40Ar-39Ar年龄及意义

玛因鄂博断裂带具有左型剪切活动特征,分布其中的花岗质糜棱岩呈脉状、条带状产出,展布方向与剪切拉伸方向一致,为同构造花岗岩。其岩石化学为高钾钙碱性系列,属后碰撞“I”型花岗岩;稀土元素含量较高,ΣREE为(239.14~266.31)×10-6;具有中等程度的铕负异常,δEu为0.45~0.66,轻稀土明显富集。其锆石U-PbSHRIMP年龄为281±4Ma,黑云母40Ar-39Ar等时线年龄为236.1±1.2Ma。二者分别代表岩石的侵入年龄和后期的剪切变形年龄。其形成与早二叠世区域性大规模剪切活动有关,而黑云母40Ar-39Ar等时线年龄代表中三叠世早期的剪切变形活动。结合前人资料分析,玛因鄂博断裂的剪切活动持续时间较长,高峰期可能为290~270Ma,而其最后结束时间为230Ma左右。     

麻阳陆相盆地东缘侏罗纪地层研究

本文对麻阳陆相盆地东缘侏罗纪地层的岩石特征、微体化石、地层层序、生物组合特征以及沉积环境进行了较系统的研究,提高了湖南西部侏罗纪地层的研究程度。     

宜章界牌岭锡多金属矿床地球化学异常模式

界牌岭锡多金属矿床是一个与浅源重熔花岗岩有关的热液多金属隐伏矿床。研究表明：矿床自上至下具有Ｆ－Ｂｅ－Ｐｂ、Ｚｎ－Ｐｂ－Ｓｎ、Ｃｕ－Ｎｂ、Ｔａ、ＴＲ的矿化分带和细脉状－层状（似层状）－面状的矿体形态分带,成晕具有Ｈｇ、Ｂ、Ｂａ、Ｃｒ、Ａｓ离心半环状晕－Ｆ、Ｂｅ、Ｌｉ、Ｐｂ、Ａｇ同心环状上偏心晕－Ｓｎ、Ｃｕ、Ｚｎ、同心环状下偏心晕－Ｎｂ、Ｇａ离心卫星晕的分布规律。据此,建立了本矿床“三环－帽壳式”地球化学异常模式。经模式识别,总结了不同剥蚀程度矿床（浅,中,深）异常评价的地质－地球化学指标。     

湖南省地质灾害分布特征及防治对策

湖南的地质环境条件和气象、水文条件,有利于多种地质灾害发生,人类经济－工程活动诱发地质灾害所占比例亦很大,各种地质灾害的发育具有明显的规律性。本文探讨了湖南省地质灾害的分区、预测及防治对策。     

鱼潭水电站地下厂房裂隙层状围岩的变形特征

通过分析鱼潭水电站地下厂房围岩松动圈、块体塌滑,应力变化和收敛位移等特征,揭示了本工程裂隙层状围岩变形破坏的一般规律。     

合肥数字地震遥测台网观测系统的设计与应用

本文主要描述了合肥数字地震遥测台网观测系统的技术原理和设计过程。认为根据台网功能和技术环境,建设一个全无线的数字地震遥测台网(由数字遥测台、数字中继站、中网接收处理中心组成)是可能的。     

Seismicity Factor A-Value and Its Application to Mid-Term Earthquake Prediction in North China

The seismicity factor A-value is defined by synthesizing the seismicity precursors in time, space and magnitude in this paper. The seismicity data of moderate or small earthquakes during 1972 ~ 1996 in North China are used to perform spacial scanning of seismicity factor A-value. The result shows that there are obviously anomaly zones of A-value with better prediction effect in the mid-term of 2~3 years before most moderately strong earthquakes. Some problems regarding the mid-term prediction using A-value have been discussed.     

Time-space Evolution Pattern and Numerical Analysis of Wave Velocity Ratios Before Lijiang and Ninglang Earthquakes

Dynamic tracing of space-time evolution pattern of wave velocity ratio before the Lijiang earthquake with M=7.0 occurred on February 3, 1996 in northwestern Yunnan. We compared the Ninglang earthquakes with M=6.7 and M=6.4 which occurred on November 7 and December 13. 1976, 90 km away from the Lijiang earthquake. We found that the space-time evolution patterns of velocity that various authors' studied at different times are very similar.Anomaly areas of wave velocity ratio with high values appeared in the seismogenic areas 5 -7 years before the strong earthquake. Anomalies with low values in large areas appeared 3-4 years before the earthquake. Once again the anomaly areas of wave velocity ratio with high values appear in a lower range 1 ~2 years before. The strong earthquake occurred in the overlapping area of two high value anomaly areas, surrounded by the anomaly areas with low values. The monthly mean values of wave velocity ratio before the two strong earthquakes had maintained low value anomalies