新疆东准双泉地区与韧-脆性剪切带有关的金矿成矿

[摘要]区域成矿背景分析表明,东准噶尔卡拉麦里地区韧-脆性剪切带形成于陆-陆碰撞体制, 在330 ~265Ma 期间,受挤压伸展体制转换影响,先后经历了韧、脆性构造变形。对与韧-脆性剪切带有 关的金矿石英流体包裹体研究发现,包裹体以气液相为主,均一温度集中在160 ~ 240益,成矿流体盐度 为3. 55 ~4. 5wt%NaCl。成矿流体的氢、氧同位素组成表明成矿流体的水为变质成因水。金属硫化物硫 同位素啄34 S 值为3. 54 ~10. 68译,显然属于混染硫。黄铁矿包裹体氦氩同位素3 He/ 4 He 值为0. 18 ~2. 18 Ra,属幔壳混源。成矿年代学研究表明,双泉金矿成矿时代及控矿构造脆性变形时间为(269依9) Ma ~ (260依4)Ma,金初始富集时间在310Ma 前后,并得到含矿花岗斑岩U-Pb 同位素年龄的支持,该事件在 东准地区均有同位素年龄记录,是区域性的构造岩浆成矿流体热事件。上述资料表明,金矿成矿过程、 成矿流体性质等在时间、空间上严格受韧-脆性剪切构造变形带控制。     

塔里木河流域适应气候变化和人类活动的应对措施

自2001年开始实施塔里木河流域近期综合治理工程,提出了以强化流域水资源统一管理和调度为核心,以源流区节水改造和干流河道治理为重点进行综合治理,积极稳妥地进行经济结构调整,实施退耕封育保护,有效保护好现有天然林草植被.通过向塔里木河下游生态输水,干涸近30a的台特玛湖于2001年11月16日开始有水,使塔里木河下游绿色走廊得到初步复苏等,流域生态环境得到极大的恢复.然而,自2007年以来,塔里木河向下游输水已大为减少,仅能输水到中游,特别是2009年水文干旱,塔里木河干流断流达1 100km多,使下游绿色走廊再度陷入生态危机.为此,需要重新审视塔里木河流域的综合治理,从加强源流治理开始,来巩固干流治理成果.认真总结10a来治理经验与教训,针对人类活动和气候变化对源流与干流造成的影响程度,积极采取应对措施.     

黑龙江五大连池火山群火山分布与断裂关系新认识

五大连池是世界陆内单成因火山的典型代表,明确断裂与火山排布关系对研究此类火山活动过程具有重要意义。通过地表观察与遥感图像解译,结合区域构造、地表出露断裂或破裂带、火山喷发时间次序(如一些火山存在由SW向NE依次喷发的规律)、区域剖面图以及不同向排布的火山规模规律等现象,研究了五大连池陆内单成因火山群火山排布与断裂的相关关系,认为五大连池地区具有NE,NW和近E-W三组方向的7条断层。区域大地电磁资料以及东北地区深部构造研究也支持这一分析。由于这三组方向的断裂还出现于火山活动之前的花岗岩之中,加之地震数据、地质历史时期的应力状态以及河流阶地研究显示在火山活动时期本地区不存在活动断裂,这些断裂应该形成于五大连池火山活动之前,并在火山作用过程中为岩浆提供了向上运移的通道,从而形成了现今的地表火山分布,即三组火山沿NE向断裂排布,两组火山沿NW向断裂分布,两组火山沿近E-W向断层排布。     

黔南-桂中地区泥盆系层序地层格架中的储集体特征研究

通过对黔南坳陷和桂中坳陷的地层对比和分析,识别出了8种层序界面标志,共划分两个超(二级)层序SS1和SS2,并讨论了各体系域特征。在层序格架中对研究区内的储集体类型进行了总结,主要包括生物礁(滩)储集体、白云岩储集体和缝洞型储集体等3种类型。对层序格架中储集体的成因类型进行了总结归纳:有利的储集体主要有TST礁滩灰岩储集体、HST礁滩灰岩、白云岩储集体。     

四川盆地中二叠统栖霞组层序——岩相古地理

随着对四川盆地碳酸盐岩储集层的重视和大力勘探,中二叠统栖霞组发育的滩相储集层成为盆地内寻找新气源的有利层位之一。文中根据岩心观察、野外剖面实测和室内镜下岩石薄片鉴定分析,并结合各种沉积相标志研究,确定研究区栖霞组主要发育浅水型碳酸盐岩台地沉积,其可进一步划分为碳酸盐岩台地相及若干亚相和微相。以Vail的层序地层学理论为指导,通过以岩性—岩相转换界面为主的层序界面识别,确定栖霞组发育2个Ⅱ型三级层序,每个层序划分出TST和HST两个沉积体系域。在沉积相和层序地层学分析的基础上,以层序格架内体系域为编图单元,用"单因素分析多因素综合作图法"编制了各体系域的岩相古地理图并对其演化特征进行了分析。结合各相带储集物性特征,认为台缘滩和台内滩为最有利储集相带,尤以SQ2-HST滩相颗粒灰岩经过白云岩化改造后更具储集意义。     

南海北部深水西区中中新世混合沉积模式及控制因素

以新采集的地震资料为基础,对南海北部深水西区的混合沉积作了初步研究。混合沉积在地震剖面上表现为平行—亚平行,振幅强—中,频率中等及连续性中等的反射特征。混合沉积分布在研究区地震资料覆盖范围的西北角,发育规模较大,最大长度达44.7km,最大宽度33.2km,面积1084km2,最大厚度为138m,纵向上分布在中中新统梅山组。综合南海北部构造演化、地震勘探等研究成果,建立了混合沉积模式。该混合沉积分布于半深海沉积区,由其南东东方向的西沙—广乐台地提供碳酸盐岩碎屑(同时也提供部分硅质碎屑),由其西侧的中南半岛提供主要的硅质碎屑。在南海北部深水西区,控制混合沉积分布的主要因素为构造作用(包括海平面变化)、物源供给及水动力条件等三个方面,这三者之间又具有密切的内在联系。     

Implication of coupled natural and human systems in sustainable rangeland ecosystem management in HKH region

The sustainable development of rangeland ecosystems, the vital ecosystems providing many important ecosystem services for millions of people in the Hindu Kush-Himalaya region is presently confronted with a number of challenges. A coupled natural and human systems approach is needed to facilitate effective collaboration among social scientists, bio/physical scientists, and management practitioners to better understand how people interact with the environment in which they live. In pursuing this argument, three existing case studies, i.e. Indigenous rangeland management in Himalayan Nepal, Cultivated Grassland Systems in Eastern Qinghai-Tibetan Plateau, and Grassland Restoration in Central Qinghai-Tibetan Plateau were synthesized in this paper to address the importance of coupled natural and human systems in promoting sustainable rangeland ecosystem management in the Hindu Kush-Himalaya (HKH) region. It was concluded although the research sites and objectives were very different, that these three case studies had many commonalities that addressed the complex interactions and feedbacks between natural and human systems, and highlighted the integration of various tools and techniques from the ecological and social sciences, as well as other disciplines, in sustainable rangeland management. These case studies have offered unique interdisciplinary insights into complexities that cannot be gained from ecological or social research alone. The results from these case studies can be applied to many other coupled systems at local, national, and global levels.     

Eutrophication,health risk assessment and spatial analysis of water quality in Gucheng Lake,China

The water characteristics of the Gucheng Lake, such as eutrophication, health and spatial distribution, were investigated. On the basis of the trophic state index (TSI) and entropy weight, a synthesized trophic state index (STSI) model was established to assess lake eutrophication condition through calculating STSI, choosing TP, TN, COD, BOD and NH₃-N as trophic variables. The STSI ranged from 50.58 to 62.44, which showed that the water has been between eutrophic and supereutrophic. A histogram was applied to health risk assessment which was analyzed from carcinogenic substances (Cr⁺⁶, As and Cd) and non-carcinogenic substances (hydroxybenzene, Pb, Hg, CN⁻ and NH₃), and the results showed that the former was much greater than the latter for effect. The total risk for each resident caused by all pollutants ranged from 5.18E-05 to 8.34E-05, which is far higher than the standard, recommended by Sweden Bureau of Environment Protection and Holland Ministry of Building and Environment Protection (1.0E-05). Cluster analysis was used to detect similarities and dissimilarities among the seven sampling sites and explain the observed clustering in terms of affected conditions. Twenty-one variables were used to divide seven sampling sites into three groups, namely, north lake, south lake and lake center.     

An Improved Time Domain Approach for Analysis of Floating Bridges Based on Dynamic Finite Element Method and State-Space Model

The floating bridge bears the dead weight and live load with buoyancy, and has wide application prospect in deep-water transportation infrastructure. The structural analysis of floating bridge is challenging due to the complicated fluid-solid coupling effects of wind and wave. In this research, a novel time domain approach combining dynamic finite element method and state-space model (SSM) is established for the refined analysis of floating bridges. The dynamic coupled effects induced by wave excitation load, radiation load and buffeting load are carefully simulated. High-precision fitted SSMs for pontoons are established to enhance the calculation efficiency of hydrodynamic radiation forces in time domain. The dispersion relation is also introduced in the analysis model to appropriately consider the phase differences of wave loads on pontoons. The proposed approach is then employed to simulate the dynamic responses of a scaled floating bridge model which has been tested under real wind and wave loads in laboratory. The numerical results are found to agree well with the test data regarding the structural responses of floating bridge under the considered environmental conditions. The proposed time domain approach is considered to be accurate and effective in simulating the structural behaviors of floating bridge under typical environmental conditions.