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991.
论中国火山次火山岩—斑岩金银矿成矿系列 总被引:12,自引:4,他引:8
研究了中国火山次火山岩-斑岩金银矿成矿系列的划分、成矿构造环境、矿床类型、成矿形式。该系列金银矿划分为6个亚系列:大陆边缘与高钾钙生英安-流纹岩有关的Ag-Au成矿亚系列;古生代岛弧区与富钠高碱玄武岩拉斑玄武岩有关的Au(Cu、Ni、Cr)成矿亚系列;陆内裂谷、裂陷区富碱高钠中基-中酸性夺有关的Au-Cu-Fe成矿亚系列;地槽褶皱带钙碱性安山-流纹质火山岩有关的Ag-Sn-Cu-Pb-Zn-(Au 相似文献
992.
σ-τ平面上莫尔理论的修正 总被引:2,自引:1,他引:1
在莫尔理论中如何引进中间主应力σ2的影响一直是长期困扰力学界的一个问题,由此产生了在σ-τ平面上难以界定某些状态下应力圆的破损界线。以静水应力σm对结合力和滑移的影响观点,将二参数的莫尔定理修正为三参数形式后,分析了它在σ-τ平面上的应用,为引进中间主应力σ2的影响提供了新途径。 相似文献
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江西省生态环境现状、存在问题和对策 总被引:1,自引:0,他引:1
近年来,江西省实现土地资源的占补平衡,但部分城市周边土地污染较为严重;森林覆盖率较高,但森林生态系统较为脆弱;大江大河水质良好,但城市江段水质较差,生活污水成为主要污染源,农业方面污染源也有加重趋势。总的来说,江西省生态环境现状总体良好,但人为因素等对生态环境所造成的破坏不容忽视,应加强领导和规划,以实现可持续发展。 相似文献
997.
CAI Chunfang PENG Licai MEI Bowen XIAO Yingkai 《《地质学报》英文版》2006,80(4):550-556
In order to elucidate the origin and migration of basinal brines in the Bachu Bulge, Tarim Basin, we have carried out analyses on chemical composition, and boron, hydrogen and oxygen isotopes of formation waters together with the XRD of clay minerals from the Paleozoic strata. The waters show Ca, B, Li and Sr enrichment and SO4 depletion in the Carboniferous and Ordovician and K enrichment in part of the Ordovician relative to seawater. The relationship between δD and δ^18O shows that all the data of the waters decline towards the Global Meteoric Water Line with the intersection of them close to the present-day local meteoric water, suggesting that modern meteoric water has mixed with evaporated seawater. The ^87Sr/^86Sr ratios range from 0.7090 to 0.7011, significantly higher than those of the contemporary seawater. The δ^11B values range from +19.7 to +32.3‰, showing a decrease with the depth and B concentrations. The results suggest that isotopically distinct B and Sr were derived from external sources. However, since the percentages of illite are shown to increase with depth among clay minerals in the study area, i.e., illite is due to precipitation rather than leaching during deeper burial, it is unlikely for illite to have contributed a significant amount of B to the waters. Thus, B with low δ^11B values is interpreted to have been added mainly from thermal degradation of kerogen or the basalts in the Cambrian and Lower Ordovician. 相似文献
998.
In this paper, based on the results of tomographic image of Tangshan and Xingtai areas, the relations between the characteristics of the two strong earthquake sequences and their three-dimensional velocity structures are studied. The research results indicate that:① Mosaic distribution of low-velocity bodies and high-velocity bodies, especially the existence of high-velocity bodies with large size in crust are the common basis of development of the two earthquake sequences. ②Scale, depth, and heterogeneity of high-velocity and low-velocity bodies are the important factors to effect the characteristic of earthquake sequences.③ The depth of the high-velocity body in Tangshan area is less than that in Xingtai area, which is the principal reason why the dominant focal depth and the biggest focal depth of Tangshan earthquake sequence are less than Xingtai's.④The depth of the high-velocity bodies in Ninghe area is more than that in Tangshan-Luanxian area, which lead to the biggest magnitude and epicentral intensity are lower. These results could be helpful for predicting the main shock of strong swarm-type earthquakes and later strong aftershocks. 相似文献
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研究了天然碳酸钙的粒度对除去K2 SO4肥料中游离酸的影响 ,实验表明 ,粒径小于0 1 49mm的天然CaCO3能有效除去游离酸 ,按m(CaCO3)∶m(K2 SO4) =4∶1 0 0的比例控制天然CaCO3的加入量 ,可使K2 SO4中的游离酸酸度小于 0 50 %。 相似文献