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991.
992.
纳日贡玛矿床是我国著名“三江”北段成矿区带中最典型的斑岩型Cu-Mo矿床。在总结矿床地质特征的基础上,通过系统总结该矿床的矿床地球化学及成矿作用相关资料,得出以下结论:①纳日贡玛矿床形成于喜马拉雅运动早期,纳日贡玛铜钼矿床成矿物质主要来自花岗斑岩体,成矿花岗斑岩源于下地壳;成矿流体为岩浆期后热液,矿床硫是由岩浆硫(为主)和成矿流体萃取围岩中的硫所组成的1种混合硫源。矿床的形成与青藏高原东缘区域构造和应力转换密切相关。②基于已有认识,建立了纳日贡玛铜钼矿床的成矿理想模式,认为矿体形成背景可能为逆冲挤压推覆条件下的局部拉张环境,拉张降压以及围岩的性质导致了该矿床富钼贫铜现况;矿床热液蚀变发育,绢云岩化与矿体较为密切,钾化带范围小,与成矿关系不大;纳日贡玛矿区剥蚀程度大,纳日贡玛矿床东南部剥蚀程度相对较小,在东南部外围找矿过程中,应该兼顾矽卡岩型矿体。 相似文献
993.
994.
锡力诺尔金矿位于二连-贺根山断裂带偏南侧,为国土资源大调查中新发现的金矿点。本文在系统研究苏左旗-阿巴嘎旗地区成矿地质背景和成矿规律基础上,对锡力诺尔金矿点的地质特征和控矿因素进行了阐述,认为金矿化体主要赋存于二叠系上统林西组的细砂岩、砂砾岩的层间破碎带中,受控于北东向韧性剪切构造带和次级张性裂隙。通过锡力诺尔金矿点与外围金矿点的对比分析,初步认为锡力诺尔金矿体的成因类型为石英脉与蚀变岩复合型,矿体主体为低品位蚀变岩型,显示出较好的找矿前景。本文可为摸清该地区的金矿找矿思路和圈定金矿找矿靶区提供借鉴。 相似文献
995.
本文导出了具有厚度和滑动弱化区域的断层的非对称地震矩张量表示式,指出要求地震矩张量具有对称性不是一个绝对必要的限制.在非对称地震矩张量中,位错项对应于对称地震矩张量,拉力项对应于非对称地震矩张量.由于拉力项等效于单力偶,所以在非对称地震矩张量解的两个节面上,沿滑动矢量方向的力偶强度不再相同,与较大力偶相联系的节面为断层面,与较小力偶相联系的节面为辅助面.这一性质可用以从两个正交的节面中判断哪一个节面是断层面.如果忽略拉力项,会高估与位错对应的标量地震矩.只有满足相应的约束条件的非对称地震矩张量才能表示具有厚度和滑动弱化区域的断层模型,并从中分离出与位错和拉力对应的地震矩张量. 相似文献
996.
997.
998.
With the rapid economic development during the last 30 years in China, more and more disparities have emerged among different regions. It has been one of the hot topics in the fields of physical geography and economic geography, and also has been the task for Chinese government to handle. Nevertheless, to quantitatively assess the impacts of physio-geographical patterns (PGP) on the regional development disparity has been ignored for a long time. In this paper, a quantitative method was adopted to assess the marginal effects of the PGP on spatio-temporal disparity using the partial determination coefficients. The paper described the construction of the evaluation model step by step following its key scientific thinking. Total GDP, per capita GDP, primary industrial output value and secondary industrial output value were employed in this study as the indicators to reflect the impacts of PGP on the regional development disparity. Based on the evaluation methods built by researchers, this study firstly analyzed the temporal impacts of the PGP on spatio-temporal disparity of the regional development in China during the past 50 years, and then explained the spatial differences at each development stage. The results show that the spatio-temporal disparity in China is highly related to the PGP, and that the marginal contribution rate could be employed as an effective way to quantitatively assess the impact of the PGP on spatio-temporal disparity of the regional development. 相似文献
999.
300年来中国森林的变化 总被引:5,自引:2,他引:3
Based on historical documents, modern survey and statistics, as well as the result of predecessor studies, the trend and main process of forest dynamics are recognized. The forest area and forest coverage rates for each province of China from 1700 to 1949 are estimated backward by every 50 years. Linking the result with modern National Forest Inventory data, the spatial-temporal dynamics of Chinese forest in recent 300 years (AD 1700-1998) is quantitatively analyzed. The study shows that in recent 300 years, the forest area in current territory of China has declined by 0.95×10^8 hm^2 (or 9.2% of the coverage rate) in total, with a trend of decrease and recovery. Before the 1960s, there was a trend of accelerated descending. The forest area was reduced by 1.66×10^8 hm^2 (or 17% of the coverage rate) in 260 years. While after the 1960s, there has been a rapid increase. The forest area increased by 0.7×10^8 hm^2 (or 8% of the coverage rate) in 40 years. The study also shows that there is a significant spatial difference in the dynamics of forest. The amplitudes of increasing and decreasing in western China are both smaller than the ones in eastern China. During the rapid declining period from 1700 to 1949, the most serious decrease appeared in the Northeast, the Southwest and the Southeast, where the coverage rate in most provinces dropped over 20%. In Heilongjiang Province, the coverage rate dropped by 50%. In Jilin Province, it dropped by 36%. In Sichuan Province and Chongqing Municipality, it dropped by 42%. In Yunnan Province, it dropped by 35%. During the recovery period 1949-1998, the western provinces, municipality and autonomous regions, including Ningxia, Gansu, Inner Mongolia, Sichuan-Chongqing, Yunnan, Tibet, Xinjiang and Qinghai, etc, the increase rates are all below 5%, while the eastern provinces, municipality and autonomous regions (except Heilongjiang, Hubei, Jiangsu-Shanghai) have achieved an increase over 5%, among which the Guangdong-Hainan, Guangxi, Anhui, Beijing-Tianjin-H 相似文献
1000.
利用雷电定位系统进行电网雷击故障快速查询 总被引:1,自引:0,他引:1
At present, lightning is one of the 10 natural disasters, and it is also the top environmental factor of power interruption. It often causes huge losses to the electric system. The Wuhan High Voltage Institute of the State Grid Corporation of China and Huazhong University of Science and Technology have been researching and developing lightning location systems (LLSs) since the late 1980s. In the mid-1990s, a lightning detection network was created in 29 provinces and cities in China. It is primarily applied to rapidly find lightning accidents, which greatly reduces power interruption. Also, it ensures high efficiency and safe operation of the electricity system. Remarkable benefit is achieved. China's LLS went through an "orientation positioning - time difference positioning - integrated positioning" development process. The positioning precision, detection efficiency, degree of automation, practicability and applied range are improved. Also, a lightning information system plan of the national network has been implemented, which services the whole society. 相似文献