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601.
运用孢粉浓缩物AMS 14C测年和氨基酸测年方法结合气候地层对比,建立神农架地区大九湖盆地DJH-2 孔的地层年代序列。依据孢粉分析结果并结合沉积环境,将大九湖盆地中更新世晚期以来的植被演替和古气候演化划分为六个阶段:① 275.0-188.0 ka,寒冷偏干,寒温带针叶林、高山草甸;② 245.0-188.0 ka,暖湿偏干,常绿、落叶阔叶混交林;③ 188.0-129.0 ka,冷干,寒温带针叶林为主,过渡为高山草甸为主;④ 129.0-71.8 ka,暖湿,暖温带落叶阔叶林;⑤71.8-15 ka,冷干,寒温带针叶林与高山草甸间隔发育,中间有喜暖种属增多的迹象;⑥ 15.0-1.0 ka,暖湿,亚热带常绿、落叶阔叶林。孢粉组合特征及单种属特征所显示的盆地气候变化反映了良好的全球冰期、间冰期气候旋回。孢粉浓度特征反映大九湖盆地气候变化受北半球高纬冰量与低纬太阳辐射的双重控制。  相似文献   
602.
The sustainable development has been seriously challenged by global climate change due to carbon emissions. As a developing country, China promised to reduce 40%-45% below the level of the year 2005 on its carbon intensity by 2020. The realization of this target depends on not only the substantive transition of society and economy at the national scale, but also the action and share of energy saving and emissions reduction at the provincial scale. Based on the method provided by the IPCC, this paper examines the spatiotemporal dynamics and dominating factors of China’s carbon intensity from energy consumption in 1997–2010. The aim is to provide scientific basis for policy making on energy conservation and carbon emission reduction in China. The results are shown as follows. Firstly, China’s carbon emissions increased from 4.16 Gt to 11.29 Gt from 1997 to 2010, with an annual growth rate of 7.15%, which was much lower than that of GDP (11.72%). Secondly, the trend of Moran’s I indicated that China’s carbon intensity has a growing spatial agglomeration at the provincial scale. The provinces with either high or low values appeared to be path-dependent or space-locked to some extent. Third, according to spatial panel econometric model, energy intensity, energy structure, industrial structure and urbanization rate were the dominating factors shaping the spatiotemporal patterns of China’s carbon intensity from energy consumption. Therefore, in order to realize the targets of energy conservation and emission reduction, China should improve the efficiency of energy utilization, optimize energy and industrial structure, choose the low-carbon urbanization approach and implement regional cooperation strategy of energy conservation and emissions reduction.  相似文献   
603.
巴姆地震地表形变的差分雷达干涉测量   总被引:7,自引:0,他引:7       下载免费PDF全文
夏耶 《地震学报》2005,27(4):423-430
利用星载合成孔径差分雷达干涉技术和ENVISAT卫星雷达数据, 获得了2003年12月26日伊朗巴姆的里氏6.5级地震引起的同震地表形变场,并详细地介绍了信号处理的过程. 利用地震前后的相干图的差异及形变场的突变棱线, 精确确定了地面上断层裂缝的位置、形状和长度. 这对震源理论模型的参数估计提供了依据. 由雷达干涉技术测量得到的形变场与理论模型模拟的结果一致.   相似文献   
604.
A self-organizing map (SOM) was used to cluster the water quality data of Xiangxi River in the Three Gorges Reservoir region. The results showed that 81 sampling sites could be divided into several groups representing different land use types. The forest dominated region had low concentrations of most nutrient variables except COD, whereas the agricultural region had high concentrations of NO3N, TN, Alkalinity, and Hardness. The sites downstream of an urban area were high in NH3N, NO2N, PO4P and TP. Redundancy analysis was used to identify the individual effects of topography and land use on river water quality. The results revealed that the watershed factors accounted for 61.7% variations of water quality in the Xiangxi River. Specifically, topographical characteristics explained 26.0% variations of water quality, land use explained 10.2%, and topography and land use together explained 25.5%. More than 50% of the variation in most water quality variables was explained by watershed characteristics. However, water quality variables which are strongly influenced by urban and industrial point source pollution (NH3N, NO2N, PO4P and TP) were not as well correlated with watershed characteristics.  相似文献   
605.
Based on data obtained from field investigations, this paper aims to analyze the influence of the river overflow on the desert riparian vegetation and discuss the function of the river overflow on the vegetation restoration at the lower Tarim River. The results show that (1) there are only 17 species, 13 genera and 9 families in the study areas before river overflow, while there are 34 species, 26 genera and 12 families after the overflowing in which 18 species emerged newly; (2) judging by the biodiversity indices, the species diversity and species richness in the river overflowed area increase more significantly than those in the un-overflow area; (3) judging by the importance of different species after years of river overflowing, the annual herbs germinate quickly at first, while the perennial herbs with deep roots or root clones become dominant in the plant community; (4) after several times of river overflowing, some arbors and shrubs such as Populus euphratica and Tamarix ramosissima germinate easily and can dominate gradually in the plant community. The results indicate that the river overflowing restores the severely degraded ecosystem in the lower Tarim River and the function is connected with restoration of eco-hydrological processes in the study areas. The results suggest that experimental overflowing has initiated a process of restoring ecosystem function within the riparian forest.  相似文献   
606.
Abstract: This paper presents the 3D density structure of crust in the Longmenshan range and adjacent areas, with constraints from seismic and density data. The density structure of crust shows that the immense boundary plane of density distribution in relation to the Longmeshan fault belt is extended downward to ~80 km deep. This density boundary plane dips towards the northwest and crosses the Moho. With the proximity to the Longmenshan fault belt, it has a larger magnitude of undulation in the upper and middle crust levels. Density changes abruptly across Longmeshan fault belt. Seismic data show that most of the earthquakes in the Longmenshan area after the 2008 Ms8.0 Wenchuan Earthquake occurred within the upper to middle crust. These earthquakes are clearly distributed in the uplifted region of the basement. A few of them occurs in the transitional zone between the uplifted and subsided areas. But most of the earthquakes distributes in transitional zone from subsided to uplifted areas in the upper and middle crust where relatively large density changes occurr The 3D density structure of crust in the Longmenshan and adjacent areas can thus help us to understand the pattern of overthrusting from the standpoint of deep crust and where the earthquakes occurred.  相似文献   
607.
西天山伊宁地块主褶皱幕鄯善运动的确立及地质意义   总被引:7,自引:0,他引:7  
地层不整合接触是研究地质发展历史及鉴定地壳运动特征和运动时期的重要依据,主褶皱幕是一造山带多幕构造运动中起决定性作用和最为重要的一次构造运动。天山的构造运动幕次多且因地而异,前人认识多有分歧,也没有确立主褶皱幕。伊宁地块伊什基里克山一带上、下石炭统之间为角度不整合接触关系,在岩石组合、沉积环境、古生物地理区系、构造样式、区域大地构造背景等方面差异最为显著,凸显了鄯善运动对区内构造格架和盆山演化起到决定性的作用,因而是主褶皱幕。鄯善运动记录了西天山沟—弧—盆格局消亡,天山残余小洋盆终结,塔里木板块和准噶尔板块最终拼合在一起,形成了统一大陆的重要演化信息。  相似文献   
608.
Two NE-SW trending wide-angle seismic profiles were surveyed across the Chinese side Two NE-SW trending wide-angle seismic profiles were surveyed across the Chinese side of the Yinggehai (莺歌海) basin (YGHB) with ocean bottom hydrophones (OBHs) and piggyback recorded by onshore stations located on the Hainan (海南)Island.Detailed velocity-depth models were obtained through traveltime modeling and partially constrained by amplitude calculations.More than 15 km Tertiary sedimentary infill within the YGHB can be divided in to three layers with distinct velocity-depth distribution.Overall,the upper layer has a high velocity gradient with 3.8-4.1 km/s at its bottom,consistent with progressive compaction and diagenesls.Its thickness increases gradually towards the basin center,reaching 4.5 km along the southern profile.The middle layer is characterized in its most part as a pronounced low velocity zone (LVZ) with average velocity as low as 3.0 km/s.Its thickness increases from 3.0 to over 4.5 km from NW towards SE.The primary causes of the velocity inversion are high accumulation rate and subsequent under-compaction of sediments.The velocity at the top of the lower layer is estimated at about 4.5 km/s.Despite strong energy source used (4 x 12L airgun array),no reflections can be observed from deeper levels within the basin.Towards NE the basin is bounded sharply by a clear and deep basement fault (Fault No.1),which seems to cut through the entire crust.A typical continental crust with low-velocity middle crust is found beneath the coast of the western Hainan Island.Its thickness is determined to be 28 km and shows no sign of crustal thinning towards the basin.The sharp change in crustal structure across Fault No.1 indicates that the fault is a strike-slip fault.The crustal structure obtained in this study clearly favors the hypothesis that the YGHB is a narrow pull-apart basin formed by strike-slip faulting of the Red River fault zone.  相似文献   
609.
Southward thrusting occurred in Late Oligocene-Early Miocene in southern East Kunlun (昆仑) Mountains formed the South Kunlun thrust (SKT). Permian strata and Triassic rocks were thrusted over the Paleocene-Eocene red-beds of Fenghuoshan (风火山) Group and Oligocene brownish red conglomerate and sandstone of Yaxicuo (雅西错) Group along SKT faults, formed tectonic slices, low-angle thrust faults, multi-scaled outliers, and nappe structures in south of Middle Kunlun fault (MKF). In addition, SKT displacement or shortening is estimated to be ~(30-35) km across Dongdatan (东大滩) valley and East Wenquan (温泉) basin. 39Ar-40Ar dating of chlorite of ductile shear zone along front thrust fault indicates that SKT thrusting occurred at 26.5±2.7 Ma, and fission track dating of apatite from mylonitic granite in SKT gives the age 26±2 Ma, corresponding to initial time of rapid uplift of East Kunlun Mountains. Thrust faults and folds of SKT were covered unconformably by Late Miocene lacustrine strata, and major thrusting of SKT ended before 13.5-14.5 Ma according to regional chronological data in northern Tibetan plateau.  相似文献   
610.
介绍了江苏省无机材料专业测试服务中心建设的背景、作用、功能和研究方向,从测试新技术在材料领域的应用研究、新材料分析测试标准方法和标准物质的研究、非金属材料物化性能研究、生态环境测试技术研究、应对国际贸易技术壁垒等方面入手,详细叙述了中心正在或将要开展的研究领域和方向,旨在更好为地方经济建设提供技术支持和技术服务功能。  相似文献   
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