火山活动与天文周期   总被引：3，自引：0，他引：3  

杨学祥  陈殿友 《地质论评》1999,45(7):33-42

  相似文献   

块状硫化物矿床研究进展评述   总被引：27，自引：4，他引：23  

顾连兴 《地质论评》1999,45(3):265-275

最近十余年来,海底块状硫化物矿床的研究在如下方面有新的进展：矿床类型,矿化和蚀变特征,矿石结构－构造和变形－变质,矿床模式和成矿机制,金属和硫的来源,成矿流体的性质和来源,以及现代海盆地中的成矿作用等。  相似文献   

多伦地区晚侏罗世火山活动节律研究   总被引：1，自引：0，他引：1  

赵国春  邓晋福  白志达  顾德林  徐德斌  孙恺荪  田明中  赵海玲  罗照华  李永华 《地质论评》1999,45(7):508-516

多伦地区的晚侏罗世火山岩地层,可划分为满克头鄂博、玛尼吐、白音高老三个火山活动小旋回,通过对其岩石组成、岩相、结构构造及其变化的研究,从地球历史演化的阶段性、周期性和不可逆性的角度,探讨了该区晚侏罗世火山活动节律特征,进而从时空尺度对火山活动节律的级别和特征进行了划分和厘定,并探讨了不同级别节律的成因。  相似文献   

山东沂水郯庐断裂带中段中生代火山岩特征及演化   总被引：11，自引：1，他引：10  

苏尚国  周珣若  顾德林 《地质论评》1999,45(7):565-571

山东沂水地区位于郯庐断裂带中段,中生代火山活动强烈。早期主要为一套高钾钙碱性系列的中型火山岩,年龄为110--125Ma,按安山岩K60估算的地壳厚度为58--62km,说明当时具造山岩石圈根,其代表的构造环境为活动大陆边缘。晚期为一套钾玄岩系列的中酸性火山岩及少量基性火山岩,年龄为69--101Ma,该期火山岩铕异常不明显,δEu=0.92（平均）,反映该期火山作用是在可能存在山根的条件下,在地幔岩石圈减薄、拉伸下形成的。郯庐断裂带内一套厚度达3200m的晚白垩世大盛群河湖相沉积岩,是造山带去根后地壳进一步拉张、伸展,在断陷盆地重兴冲冲的产物。  相似文献   

Hydrodynamics of suspended particulate matter in the tidal freshwater zone of a macrotidal estuary (the Seine Estuary, France)     

Loïc Guézennec  Robert Lafite  Jean-Paul Dupont  Robert Meyer  Dominique Boust 《Estuaries and Coasts》1999,22(3):717-727

The effects of fortnightly, semidiurnal, and quaterdiurnal lunar tidal cycles on suspended particle concentrations in the tidal freshwater zone of the Seine macrotidal estuary were studied during periods of medium to low freshwater flow. Long-term records of turbidity show semidiurnal and spring-neap erosion-sedimentation cycles. During spring tide, the rise in low tide levels in the upper estuary leads to storage of water in the upper estuary. This increases residence time of water and suspended particulate matter (SPM). During spring tide periods, significant tidal pumping, measured by flux calculations, prevents SPM transit to the middle estuary which is characterized by the turbidity maximum zone. On a long-term basis, this tidal pumping allows marine particles to move upstream for several tens of kilometers into the upper estuary. At the end of the spring tide period, when the concentrations of suspended particulate matter are at their peak values and the low-tide level drops, the transport of suspended particulate matter to the middle estuary reaches its highest point. This period of maximum turbidity is of short duration because a significant amount of the SPM settles during neap tide. The particles, which settle under these conditions, are trapped in the upper estuary and cannot be moved to the zone of maximum turbidity until the next spring tide. From the upper estuary to the zone of maximum turbidity, particulate transport is generated by pulses at the start of the spring-neap tide transition period.  相似文献   

胶东大庄子金矿地质特征与成因探讨   总被引：1，自引：0，他引：1  

朱大岗  吕古贤  邓军  鲁安怀 《地质与资源》1999,8(2):81-86

大庄子金矿是我国首次发现赋存于胶东变质岩中大规模韧-脆性剪切带内的蚀变岩型及石英脉型金矿床.金矿化与绢英岩化、黄铁矿化、硅化和碎裂岩化有关.矿体受韧-脆性剪切带、黄铁绢英岩化、晚元古代晚期角闪岩相变质岩的共同控制.矿石矿物组合以自然金-金属硫化物-架状硅酸盐为主的组合类型.矿床属于在韧-脆性剪切作用下,与含金量较高的下元古界荆山群变质岩的形成、演化有成因联系的蚀变、重熔、交代中温动力热液改造型金矿床.  相似文献   

试论造山带成山运动与环境变化调查方法--以东昆仑1:25万冬给措纳湖幅区调为例   总被引：1，自引：0，他引：1  

于庆文  李长安  张克信  古凤宝 《地质通报》1999,(1)

造山带演化可分为两个阶段：造山期和成山期。造山期地质调查一直是我国区调工作的重点,调查的内容以区内基础地质特征研究为主。而成山期地质调查过去一直被忽视,这也正是当前“扩大区调服务领域”所要探讨的问题。造山带成山期区域地质调查重点是：①造山带隆升的过程与特点;②山脉隆升的环境效应;③造山带现代构造运动与地质灾害。笔者结合东昆仑造山带１∶２５万冬给措纳湖幅和兴海县幅区调,对成山运动和环境变化进行讨论。  相似文献   

WAVELET CHARACTERISTICS OF RAINFALL VARIATION IN THE THREE GORGE REGION OF CHANGJIANG RIVER^*          下载免费PDF全文

Gu Xiangqian  Cao Hongxing  Gao Xiang 《Acta Meteorologica Sinica》1999,13(2):249-256

Making the climatic diagnosis of Changjiang Three Gorge Region by the maximum entropy spectrum analysis and wavelet analysis,we discovered that the main periods of the annual and wintertime precipitation variation in the east subregion differ from that in the west subregion.The former is a period of about 2 years,and the latter is about 5-6 years.Their wavelet patterns are also apparently different between two subregions:the alternate positive and negative wavelet patterns for the west,but not so regular for the east.These provide a climatic background for the implementation of Three Gorge Project.We also found that the historical reason of the main periods by combing synthetically spectrum analysis and wavelet analysis could be realized.In addition we suggest a gist of the climate forecast by analogy analysis based on the 2-dimensional wavelet figures.  相似文献   

华北地区GPS形变测量结果及其地震地质意义   总被引：9，自引：3，他引：6       下载免费PDF全文

顾国华  王若柏  孙惠娟  孙汉荣  杨春花 《地震地质》1999,21(2):2-104

简要介绍了华北地区ＧＰＳ形变监测网１９９５～１９９６年两次观测概况,利用伯尔尼软件进行数据处理的主要过程、水平形变计算与应变分析的方法和结果及垂直形变的结果。分析了ＧＰＳ成果的地震地质意义,认为ＧＰＳ观测到的水平形变可能反映了上地壳层块构造活动的某些特征  相似文献   

延庆怀来地区高分辨率浅地震反射剖面   总被引：9，自引：2，他引：7       下载免费PDF全文

刘保金  孙振国  赵成斌  顾梦林  李长法  冷欣荣  李德庆 《地震地质》1999,21(4):425-430

在延庆怀来地区穿过深断裂位置开展的浅地震反射测量获得了高分辨率的地壳浅部结构图像。结果表明,研究区内浅层断裂发育,覆盖层分层清晰,具有良好的反射性质。基底为前震旦纪地层,埋深500 ～1 000m 不等,由一系列无规律的弱反射构成。狼山断裂是延矾盆地北缘的控制性断裂,在剖面上呈铲形,反映了年轻发育阶段的伸展构造特征  相似文献