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901.
902.
卡拉盖雷铜金矿床位于新疆西天山那拉提构造带境内西段,为近年在该成矿带内发现的首例以Cu为主,伴生Au、Co等的火山岩型热液矿床。δD、δ18O分析结果表明,成矿流体在早—中阶段以岩浆热液为主,晚阶段有大气降水加入。δ34S分析结果表明,硫源主要来自深部地壳或上地幔,并有地层硫混入。铅同位素分析表明,矿区铅源为壳、幔混合俯冲带铅。辉钼矿的Re-Os同位素模式年龄为(259.6±9.7)Ma,说明矿床早阶段的成矿年龄为早二叠世末期。笔者进一步探讨了矿床成因,认为大哈拉军山组火山岩为早期矿源层;在晚石炭世后碰撞伸展阶段,来自地壳深部的含矿岩浆热液沿区域深大断裂、火山通道及浅部断裂系统运移并萃取早期矿质元素,于有利构造部位形成矿体。 相似文献
903.
904.
Decomposition and Evolution of Intracontinental Strike-Slip Faults in Eastern Tibetan Plateau 总被引:2,自引:0,他引:2
Little attention had been paid to the intracontinental strike-slip faults of the Tibetan Plateau. Since the discovery of the Longriba fault using re-measured GPS data in 2003, an increasing amount of attention has been paid to this neglected fault. The local relief and transverse swath profile show that the Longriba fault is the boundary line that separates the high and flat tomography of the Tibet plateau from the high and precipitous tomography of Orogen. In addition, GPS data shows that the Longriba fault is the boundary line where the migratory direction of the Bayan Har block changed from eastward to southeastward. The GPS data shows that the Longriba fault is the boundary fault of the sub-blocks of the eastern Bayan Har block. We built three-dimensional models containing the Longriba fault and the middle segment of the Longmenshan fault, across the Bayan Har block and the Sichuan Basin. A nonlinear finite element method was used to simulate the fault behavior and the block deformation of the Eastern Tibetan Plateau. The results show that the low resistivity and low velocity layer acts as a detachment layer, which causes the overlying blocks to move southeastward. The detachment layer also controls the vertical and horizontal deformation of the rigid Bayan Har block and leads to accumulation strain on the edge of the layer where the Longmenshan thrust is located. After a sufficient amount of strain has been accumulated on the Longmenshan fault, a large earthquake occurs, such as the 2008 Wenchuan earthquake. The strike slip activity of the Longriba fault, which is above the low resistivity and low velocity layer, partitions the lateral displacements of the Bayan Har block and adjusts the direction of motion of the Bayan Har block, from the eastward moving Ahba sub-block in the west to southeastward moving Longmenshan sub-block in the east. 相似文献
905.
906.
天山乌鲁木齐河流域山区降水δ18O和δD 特征及水汽来源分析 总被引:1,自引:0,他引:1
依据乌鲁木齐河流域山区3个站点实测次降水δ18O和δD数据以及气象观测资料,结合临近GNIP(Global Network of Isotopes in Precipitation)站点数据,对其降水δ18O和δD特征及水汽来源进行了分析。结果表明,大气降水中δ18O值波动范围大,但呈现明显的季节性变化:冬季降水δ18O较低,夏季降水δ18O较高。受流域山区气候和地理条件影响,从上游到下游各站点大气降水线截距和斜率均呈现逐渐减小趋势。大气降水中δ18O和δD与日均气温存在密切正相关关系,且温度与δ18O之间的相关性优于δD。降水中d-excess值也表现出季节性变化,冬季降水d-excess值高于夏季降水。利用HYSPLIT 4.0气团轨迹模型,得出夏季水汽主要来源西风环流输送,冬季受西风环流和极地气团共同影响。 相似文献
907.
Xiao Ziniu Zhong Qi Yin Zhiqiang Zhou Limin Song Yan Han Yanben Huang Cong Pan Jing Zhao Liang 《地球科学进展》2013,28(12):1335-1348
Role of solar activity on modern climate change, particularly in the decadal scale is an important scientific issue. This paper reviews the recent observation of decadal solar signal in earth’s climate, with focus on the mechanism of solar radiation, ultraviolet radiation and cosmic rays on climate system ,and its validation. The paper points out that the assessment of uncertainty in observations, amplification process of the climate system, as well as possible future impact of solar extreme events are challenges in the present study. Finally, the keys of breakthrough are pointed, to provide a reference for future research. 相似文献
908.
Yinhuang Irrigation District in Ningxia, as the top rice production area of high quality and quantity, has a long history in rice planting. The studies of the effective measures for the rice production replying the climate change were very important for reducing the harm of the future climate change and crop supply safety in Ningxia Province. Based on the coupling of the PRECIS model and the crop model CERES Rice, the effects of climate change on the rice production and growth stage in Yinhuang Irrigation District in Ningxia Province were simulated and evaluated, and the adaptability measures of rice production were studied. The results showed that the CERES Rice model had the preferable simulation capability, and the modified PRECIS model also could preferably simulate the required climate parameter. The crop model simulation results showed that the climate change had some influence on the rice production and growth stage in Yinhuang Irrigation District. The rice production goes down under future climate change scenarios in Ningxia Province. The trend of reduction of 2050s is more apparent than that of 2020s under the same scenarios,but the spatial change trend is similar. The extent and range of reduction of A2 scenario are wider than that of B2 scenario in the same period, but spatial change trend is different. For the change of growth stage, there has no obvious change in the north and the central part of the Yinhuang Irrigation District. The duration in 2050s shortens more obviously than that of 2020s under the same scenario, and the duration under B2 scenario shortens more obviously than that under A2 scenario in the same period. The results of adjusting the sowing date and the rice variety parameter G4 showed that the negative impact of climate change on the rice production can be reduced by sowing date advance in Yinhuang Irrigation District in Ningxia Province. There has obvious difference for the optimal G4 values of different region in Yinhuang Irrigation District, and the rice production can also be effectively upraised by adjusting the rice variety characteristic and cultivating the heat resistant rice varieties. The optimal G4 values can mitigate the damage of climate change on the rice production in Yinhuang Irrigation District in Ningxia Province. 相似文献
909.
利用美国NCEP/NCAR的再分析资料、Hadley中心逐月海温资料(HadiSST)和辽宁地区逐日降水资料,对辽宁区域性春旱大气环流特征及影响因子进行分析。结果表明:乌山脊和东亚大槽减弱,位相比历年平均位相偏东,中高纬大气环流经向度减小,是导致中国辽宁区域性春季降水减少的大气环流背景;区域性春旱同期,大陆气压升高,海上气压降低;辽宁上空湿度明显小于历年均值,贝湖到中国辽宁一带盛行西北气流。区域性春旱前冬,辽宁上空200hPa高度场出现正距平;地面气温较历史同期偏高;Nino3海温异常偏低。 相似文献
910.