排序方式： 共有12条查询结果，搜索用时 15 毫秒
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华北地台东北部前寒武纪地壳演化与铀成矿旋回 总被引：1，自引：0，他引：1
本文以研究华北地台东北部前寒武纪地壳演化为基础,阐明了该区不同地质构造单元中铀的分布与富集规律。根据铀矿化与铀源体的空间分布关系、硫同位素组成、稀上元素分布模式及同位素年龄等资料,论述了该区前寒武纪铀成矿作用具有同源性相多阶段复成因的特点。在此基础上,提出了铀成矿旋回的概念,并将华北地台东北部前寒武纪构造区存在的铀矿化划分为晚太古代、早元古代和中-晚元古代三个成矿旋回。 相似文献
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Landslides - Rockslide-debris flow may cause catastrophic damages because of its high speed and long run-out distance. The influences of slope gradient and gully channel on the entrainment,... 相似文献
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敦化—密山断裂带（二道甸子—大山嘴子段）断裂活动性评价 总被引：5，自引：0，他引：5
敦密断裂带是发育历史长、活动期次多的区域性大断裂,其形成时代及不同时代的活动性务学性质不同。为评价敦化及周围地区的区域地壳稳定性,借助于断层泥热释光测定、断裂气测量及地震、火山资料对断裂带的没部位做出了稳定和相对稳定的定量结论。 相似文献
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GPM技术及其在埋藏喀斯特勘查中的应用⒇——以南京汤山直立人化石地点洞穴为例 总被引：3，自引：0，他引：3
ＧＰＭ是通过观测点、线、面不同高度的地球磁场总强度来获取研究目标的磁场信息与背景磁场强度的。根据差异界面、扰动效应和尖端效应等原则并结合具体的边界条件,判别目标体的存在与否以及存在的大致空间形式。以往的一些工作和汤山精密磁测的研究结果表明,只要深刻研究喀斯特的磁效应和边界条件,ＧＰＭ技术就可有效地勘查埋藏喀斯特。 相似文献
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介绍了低频声纳在浅海水下检波器定位中的工作原理,分析了低频声纳在浅海定位中存在的技术难点,进行了检波器接收声纳信号、仪器采集声纳信号的测试及试验,并对测试结果进行了分析,得到声纳信号作为初至波震源的研究结论,明确了下一步的研究方向。 相似文献
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Types, Metallogenic Environments and Characteristics of Temporal and Spatial Distribution of Copper Deposits in China 总被引：2，自引：0，他引：2
Based upon a comprehensive study of 123 copper deposits in China. this paper reaches the following conclusions: 1. The crust in China was solidified pretty late; with the accretion of the plate, the copper mineralization moved towards its margin in space and became successively younger in age. 2. The major copper ore types ever found in the world have mostly been discovered in China, in which the porphyry type seems to be the most important and the massive sulfide type in the transitional bed between marine clastic and carbonate rocks is clearly defined. 3. Carbonate strata are widespread in China and their deposition lasted for a long geological period, so the proportion of copper deposits occurring in them is large as compared with other parts of the world. 4. Seven metallogenic epochs can be recognized, in which the Mesozoic one plays the leading role and the middle(late) Palaeozoic and Cenozoic ones are next in importance. Mineralization was comparatively simple in the early geological period. and became diversified later on. In the early epochs copper deposits related to basaltic magmatism and metamorphosed marine sediments predominated, whereas in the later epochs those related to granitic magmatism and continental sedimentation were dominant. 5. There exist in China thirteen metallogenic provinces, of which the Lower Yangtze downwarping belt, Sanjiang fold system, Jiangnan axis and Xikang-Yunnan axis are of greater significance. 6. The crustal mobility in China was rather pronounced, the polycyclic evolution of the crust has resulted in such obvious phenomena as the inheritance of mineralization, the coexistence of various types and the superposition of different genetic types. 相似文献
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文中利用卫星和地面观测资料分析了中国地区总云量和低云量的分布及华南沿海、华东地区和北方地区的云量垂直分布。利用CREM模式模拟了中国地区的云量,并初步分析了模拟误差的原因。模拟表明,模式能较好地再现中国地区云量水平和垂直分布的形势和演变趋势,但对总云量和低云量模拟系统性偏小20％,且模拟的华南沿海云量垂直分布大值中心偏低。初步分析认为这种云量大小的误差是云量诊断方案的经验系数值不适当引起的。 相似文献
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