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281.
黔东南地区下江群是分布在江南造山带西段的一套前寒武纪浅变质陆源碎屑岩夹火山碎屑岩组合, 其地层时代归属与划分特别是区域地层对比一直未能得到很好解决.在对该区前寒武纪地层广泛而详细的剖面测制和地质调查基础上, 运用LA-ICP-MS技术, 对地层中沉凝灰岩、含凝灰质碎屑岩和碎屑岩进行锆石U-Pb年代学测试, 获得一批高精度的年龄.四堡群河村组顶部的碎屑岩和下江群乌叶组第1段顶部的含凝灰质碎屑岩、清水江组底部与中部的沉凝灰岩、平略组中上部的含凝灰质碎屑岩、隆里组中下部的碎屑岩等样品中锆石U-Pb最小年龄组的加权平均年龄分别为819.8±6.4Ma和779.5±4.7Ma、764.0±6.3Ma与(756.8±7.6Ma、756.0±13.0Ma)、733.9±8.8Ma及725.0±10.0Ma.这些数据将四堡群和下江群的时代限制为新元古代.结合研究区隆里组与长安组整合接触关系和全球低纬度南华系冰期起始年龄(717.4Ma)的地质事实, 将下江群沉积时限约束在815~717Ma之间.根据区域岩浆事件进一步约束了下江群各组段的地层时限, 并开展江南造山带下江群及其相当层位的地层划分与对比, 认为新元古代岩浆作用制约着黔东南下江群盆地的演化. 相似文献
282.
郁山铝土矿床是2006年河南省地质调查院在豫西新安县发现的一个大型隐伏铝土矿矿床。文章通过利用显微镜、X衍射、扫描电镜、电子探针、红外光谱、热重等手段分析发现,郁山铝土矿中的矿物组成有:铝矿物,黏土矿物,铁矿物,钛矿物,非晶质,其它微量矿物(锆石、电气石、硫磷铝锶矿、明矾石、斜长石、钾长石、石英、方解石)六大类。非晶质组分的存在是华北陆块南缘铝土矿研究中物质组分方面的一个突破,为华北陆块南缘铝土矿的物质来源,成矿过程以及物质成分变化研究提供了线索和证据。 相似文献
283.
Zeng Jingjing Qu Jiansheng Pei Huijuan Dong Liping Liao Qin Liu Yanfei Zhang Zhiqiang 《地球科学进展》2015,30(11):1210-1217
The international climate change negotiation has been carried out over 20 years. The issue of climate change has shifted from a scientific question into a complex political matter which is related to the sustainable development of mankind. Based on the overview of major processes and stages of international climate conferences, this paper analyzed the key measures that major countries have taken to address climate change, as well as the primary tasks of Paris climate conference and recent international actions. The recent international climate policy issues were also analyzed in order to provide suggestions for China’s activel participation in the development of a new round of international climate change system. 相似文献
284.
Lan Chen Chen Jing an Zeng Yan Guo Jianyang Zhang Runyu Wang Jingfu Yang Haiquan Ji Yongxue 《地球科学进展》2015,30(10):1172-1181
Deep lakes always maintain vertical thermal stratification due to their physical structure. The thermocline prevents the transfer of oxygen from epilimnion to hypolimnion, leading to the formation of anoxic conditions in deeper water, the enhanced release of endogenous pollutants and the deterioration of water quality. Oxygenation is an effective measure to improve the water quality of deep lakes and mitigate the release of endogenous pollutants via the increase of the oxygen level in water. This paper provided an overview of the method and theory of oxygenation in deep lakes. Advantages and limitations of different methods of oxygenation, including artificial destratification, airlift aerators, Speece cone and bubble plume diffusers, were discussed. In addition, challenges and prospects of oxygenation were assessed based on the analyzing of typical examples of oxygenation in deep lakes and the difference in oxygenation system used in deep lakes and shallow lakes. 相似文献
285.
Hyun-Chul Lee Thomas L. Delworth Anthony Rosati Rong Zhang Whit G. Anderson Fanrong Zeng Charles A. Stock Anand Gnanadesikan Keith W. Dixon Stephen M. Griffies 《Climate Dynamics》2013,40(1-2):327-340
The impact of climate warming on the upper layer of the Bering Sea is investigated by using a high-resolution coupled global climate model. The model is forced by increasing atmospheric CO2 at a rate of 1% per year until CO2 reaches double its initial value (after 70 years), after which it is held constant. In response to this forcing, the upper layer of the Bering Sea warms by about 2°C in the southeastern shelf and by a little more than 1°C in the western basin. The wintertime ventilation to the permanent thermocline weakens in the western Bering Sea. After CO2 doubling, the southeastern shelf of the Bering Sea becomes almost ice-free in March, and the stratification of the upper layer strengthens in May and June. Changes of physical condition due to the climate warming would impact the pre-condition of spring bio-productivity in the southeastern shelf. 相似文献
286.
287.
Accuracy validation of TRMM Multisatellite Precipitation Analysis daily precipitation products in the Lancang River Basin of China 总被引:1,自引:0,他引:1
Hongwei Zeng Lijuan Li Jinming Hu Liqiao Liang Jiuyi Li Bin Li Kai Zhang 《Theoretical and Applied Climatology》2013,112(3-4):389-401
Using statistical methods and contingency table method, this paper evaluates the accuracy of 12 years (1998–2009) Tropical Rainfall Measuring Mission Multisatellite Precipitation Analysis (TMPA) daily-accumulated precipitation products within a year, the dry season, and rain season for each of the five subbasins and for each grid point (0.25?×?0.25°) in the Lancang River basin by comparing the results with data from the 35 rain gauges. The results indicate that TMPA daily precipitation estimates tend to show an underestimation comparing to the rain gauge daily precipitations under any scenarios, especially for the middle stream in the dry season. The accuracy of TMPA-averaged precipitation deteriorates with the increase of elevation at both basin and grid scale, with upstream and downstream having the worst and best accuracy, respectively. A fair capability was shown when using daily TMPA accumulations to detect rain events at drizzle rain and this capability improves with the increase of elevation. However, the capability deteriorates when it is used to detect moderate rain and heavy rain events. The accuracy of TMPA precipitation estimate products is better in the rain season than in the dry season at all scenarios. Time difference and elevation are the main factors that have impact on the accuracy of TMPA daily-accumulated precipitation products. 相似文献
288.
南秦岭主要类型热水沉积岩的REE地球化学 总被引:1,自引:0,他引:1
南秦岭泥盆纪沉积柱中产有多种类型海底热水沉积岩.它们的ΣREE偏低(平均63.09×10-6),REE配分曲线平缓右倾,La/Yb=2~8,Ce亏损,总体上与海水相似。产于Sedex含矿层中的热水沉积岩具有正Eu异常,与现代海底热液及红海热液沉积物可比;而产在Sedex含矿层以下地层中的热水沉积岩Eu亏损,与EPR热液沉积物相似。REE地球化学研究和岩石学研究结果一致,支持热水沉积岩REE来源于海水及部分下伏沉积柱(包括基底),含矿热水沉积岩是盆地热演化到一定阶段具有一定深度和规模的循环对流体系在海底的化学沉积,而Sedex含矿层以下地层中的热水沉积岩则是浅部热水对流循环的海底显示.成岩和变质作用对岩石的REE未造成影响。 相似文献
289.
研究了贵州省三板溪水库蓄水前后的地震活动特征与地震成因类型, 认为三板溪水库蓄水后出现的地震成因类型可划分为水库诱发构造型和地壳表层卸荷型。 相似文献
290.
Results of numerical simulation of currents in the western North Tropical Pacific Ocean by using a barotropic primitive equation model with fine horizontal resolution agreed well with observations and showed that the Mindanao Cyclonic Eddy located north of the equator and east of Mindanao Island exists during most of the year with monthly (and large seasonal) variations in scope . strength and central location . In June , an anticyclonic eddy occurs northeast of Halmahera Island, strengthens to maximum in August , exists until October and then disappears . The observed large-scale circulation systems such as the North Equatorial Current . the Mindanao Current and the North Equatorial Countercurrent are all very well reproduced in the simulations. 相似文献