混沌时间序列预测的局域法在边坡变形分析中的应用

边坡作为一个复杂系统,其本身的各种参量是不确定的和随机的,在其演化过程中,表现出复杂的非线性行为,发生一系列的混沌现象。本文运用现代混沌理论,对边坡变形的预测问题进行探索性研究,把混沌时间序列理论引入到边坡工程研究中,对该理论的建立及预测方法进行系统地讨论,为该领域的研究提供完整的技术方法。通过对新滩滑坡的研究结果表明,混沌时间序列方法对混沌序列的预测较线性时间序列具有较高的精度。     

Susceptibility of fish to Chattonella marina is determined by its tolerance to hypoxia

The harmful alga Chattonella marina has caused massive fish kills and economic losses worldwide. However, the fish kill mechanisms by C. marina have not been identified. The present study has confirmed that a significant elevation of blood osmolality is the universal response in moribund fish exposed to C. marina and the possible reasons leading to contradictory reports were identified. Both osmotic distress and respiratory impairment are important mechanisms leading to fish kill by C. marina. The susceptibility of marine fish to C. marina appears to be inversely related to their tolerance to hypoxia, with the hypoxia intolerant goldlined seabream being the most susceptible, and the hypoxia tolerant green grouper being the most tolerant to C. marina. Further studies in the marine medaka (Oryzias melastigma) showed that fish susceptibility to C. marina is directly related to susceptibility of the fish to hypoxia, but not related to its tolerance to hypersalinity stress.     

缅甸孟帕亚7.2级地震及其对云南强震活动趋势的意义

20世纪云南地区6.7级以上地震具有时空丛集分布特点。在1996年丽江7.0级地震结束云南地区20世纪第Ⅳ强震活跃期后,21世纪强震活跃期首发大震研究成为地震形势跟踪的重点。2011年3月24日,滇、缅交界缅甸境内发生孟帕亚7.2级地震,震中距中缅边界仅80km。该地震的动力及地震带、区归属对云南地区6.7级以上地震活动统计特征及其大震形势研判有重要影响。根据地表破裂及余震的空间展布等证据判断,发震断裂为穿越中缅两国的NE向孟帕亚-勐腊断裂(国外称之为Nam Ma断裂)。事实上,北起云南腾冲、龙陵一带,南至泰、缅、老交界地区,近等间距平行展布一系列包括孟帕亚-勐腊断裂在内的NE向断裂,其中绝大多数在历史上都发生过7级地震,而这些7级地震在空间上又构成了一条非常清晰的NNW向地震密集条带,它同样穿越了滇、缅、泰、老多地。区域大地构造演化、现今地壳运动状态及地震活动特征的综合分析表明,孟帕亚7.2级地震与传统划定的云南地区西南部的地震活动动力同源,构造相连,应归属滇西南地震带上的地震;进而应纳入云南地区6.7级以上地震活动特征的统计研究中。由此认为,缅甸孟帕亚7.2级地震拉开了云南地区21世纪首轮强震活跃期的序幕。     

Dynamic Changes of Sediment Discharge and the Influencing Factors in the Yellow River,China, for the Recent 90 Years

The dynamic changes in the sediment discharge over 90 years from 1919 to 2008 in the Yellow River in China were assessed on the basis of annual rainfall series and annual sediment series in Shan County hydrological station. The key factors affecting sediment discharge, such as rainfall, and human activities were studied. Anomaly accumulation method and double mass curve were employed to test the stage changes of sediment discharge, and to determine the main factors of sediment decline. Results showed that the annual average sediment discharge under natural conditions was about 16 × 10⁸ t, but the measured annual average sediment during 1919–2008 was 12.71 × 10⁸ t. The highest annual average during the study period was 39.10 × 10⁸ t in 1933 while the lowest was 1.77 × 10⁸ t in 2008. Sediment discharge in the Yellow River experienced two low sediment stages (1924–1931 and 1979–2008) and a high sediment stage (1932–1971), respectively. Since 1979, there was a significant decreasing trend in the sediment discharge, and the main influencing factor was fierce human activities. Annual average sediment discharge in the post‐development period (1979–2008) was 69.7% lower than that in the pre‐development period (1919–1978), with average reduction of 81 and 19% caused by human activities and rainfall, respectively. These results provide important evidence for making protecting policy for water resources quality and environmental safety of the Yellow River.     

西藏冈底斯带始新世曲水岩基的岩浆混合作用:来自斜长石阴极发光特征和成分变化的证据

斜长石作为主要造岩矿物,是研究岩石成因、示踪岩浆演化和岩浆混合过程的有效工具.对冈底斯带曲水岩基始新世花岗闪长岩、二长花岗岩、闪长岩脉和暗色包体中的斜长石进行了阴极发光图像结构特征、电子探针主量元素和LA-ICP-MS微量元素成分的分析,揭示了斜长石复杂环带的成因和相关的岩浆过程.该区斜长石的阴极发光图像呈现出多种颜色且与其An值相对应,随着An值降低依次为绿色、蓝色和暗灰色或暗红色等,并发育补丁状环带、筛状环带、韵律环带等.花岗闪长岩、二长花岗岩中斜长石的An值具有相似的变化范围(20~55),而闪长岩脉和暗色包体中An值的变化范围较大(25~85),表明曲水岩基经历了复杂的开放过程.微量元素结果表明:花岗闪长岩与闪长岩脉和暗色微粒包体具有相同的Sr含量范围(600×10^-6~1 100×10^-6);而二长花岗岩的Sr含量(1 000×10^-6~2 400×10^-6)整体高于前者.以上研究表明,花岗闪长岩中阴极发光呈现绿色的核部或幔部是偏中性岩浆注入寄主岩岩浆混合的结果;具有高Sr含量的二长花岗岩认为是高Sr含量的岩浆结晶形成的;闪长岩脉和暗色微粒包体中的筛状结构斜长石为寄主岩捕掳晶.     

Extensive Resetting of Feldspar Pb Isotopic Composition in Archean–Paleoproterozoic Granitic Rocks from the Kongling Terrane, South China: Implications for Tracing Thermal Evolutionary History

Feldspar Pb isotopes have been widely used to trace magmatic formation and evolution processes. However, it remains unclear whether post-magmatic thermal events can affect feldspar Pb isotopic ratios. Here, the in situ Pb isotopic composition of feldspar hosted in granitic rocks (thirteen Archean and one Paleoproterozoic) from the northern Kongling terrane, Yangtze Craton, South China, is analyzed. The samples reveal a substantial variation in their Pb isotopic composition, spanning the gap between the 1.9 Ga and present-day geochrons, which indicates extensive resetting by later tectonothermal events. This resetting was interpreted to have likely resulted from Paleoproterozoic and Neoproterozoic tectonothermal events related to the assembly and breakup of the Columbia and Rodinia supercontinents. These results suggest that Pb isotopes should be used cautiously when tracing magma sources and petrogenesis in magmatic rocks that have experienced post-magmatic reworking. However, the in situ Pb isotopic composition of feldspar in ancient granitoids may also potentially be used to reveal later tectonothermal events. The extensive resetting of the Pb isotopic composition in feldspar by regional thermal events may also provide new insights into our understanding of the Pb isotope paradox.     

越南红河断裂活动性研究

通过中越两国对越南红河断裂带开展的联合野外考察,获取了地震、地质、地貌和年代学等反映该断裂最新活动的相关证据。综合研究表明,越南红河断裂带第四纪以来的右旋走滑活动延续和保持了在中国境内自北向南逐渐减弱的总体趋势。其第四纪主要活动时代为中更新世中晚期,且总体活动水平明显低于中国云南境内部分,特别是自晚更新世以来越南红河断裂带的活动已表现得十分微弱。结合断裂现今地震活动和区域GPS大地形变特征分析认为,自晚第四纪以来,来自青藏高原的"侧向挤出"动力作用对红河断裂右旋走滑活动在时间、空间和强度等方面的影响可能非常有限。文中还探讨了造成这一有限影响可能的大地构造和深部构造原因     

20世纪90年代末东亚冬季风年代际变化特征及其内动力成因

为纪念陶诗言先生对东亚冬季风研究的杰出贡献,本文利用我国测站、NCEP/NCAR和ERA-40/ERA-Interim再分析资料分析了我国冬季气温和东亚冬季风在20世纪90年代末所发生的年代际跃变特征及其内动力成因。分析结果表明:从20世纪90年代末之后,我国冬季气温和东亚冬季风发生了明显的年代际跃变。从1999年之后,随着东亚冬季风从偏弱变偏强,我国冬季气温变化从全国一致变化型变成南北振荡型（即北冷南暖型）,并由于从1999年之后我国北方冬季气温从偏高变成偏低,故冬季低温雪暴冰冻灾害频繁发生,同时,我国冬季气温和东亚冬季风年际变化在此时期从以往3～4 a周期年际变化变成2～8 a周期;并且,结果还表明了东亚冬季风此次年代际变化是由于西伯利亚高压和阿留申低压的加强所致。本文还从北极涛动（AO）和北半球准定常行星波活动的动力理论进一步讨论了此次东亚冬季风年代际跃变的内动力成因及其机理,结果表明:从20世纪90年代末之后,北半球冬季准定常行星波在高纬地区沿极地波导传播到平流层加强,而沿低纬波导传播到副热带对流层上层减弱,这造成了行星波E-P通量在高纬度地区对流层和平流层辐合加强,而在副热带地区对流层中、上层辐散加强,因而导致了北半球高纬度地区从对流层到平流层纬向平均纬向流和欧亚上空极锋急流减弱,而副热带急流加强,这造成了AO减弱和东亚冬季风加强。     

1992—2012杭州湾海域生物多样性的变化趋势及原因分析

本文依据浙江省舟山海洋生态环境监测站(1992—2012年)20年的杭州湾生态环境质量监测数据,对杭州湾海洋生物多样性的现状及发展趋势进行了分析,并结合环境因子对生物多样性的变化原因进行了探讨。结果表明:杭州湾海域生物生存环境较为恶劣,生物多样性较低,生物群落结构简单,种类较少。20年间,杭州湾海域生物多样性的变化可大体分为2个阶段,第一阶段是20世纪90年代初至2000年,杭州湾生物群落的各项指标普遍呈现下降的趋势;第二阶段是2000年后至今,由于各项生态环境保护措施加强,杭州湾生物群落得到一定程度的恢复。相关性分析表明,DIN、DIP、COD和富营养化对杭州湾海域生物多样性产生了显著的影响。20年来杭州湾海域生物多样性的变化主要受人类活动的影响,污水排放导致的富营养化对生物多样性的丧失也有很大影响,滩涂围垦等沿海开发使海洋生物栖息地片段化,单调化,加速了生物多样性的降低。     

Cambrian integrative stratigraphy and timescale of China

The Cambrian Period is the first period of the Phanerozoic Eon and witnessed the explosive appearance of the metazoans, representing the beginning of the modern earth-life system characterized by animals in contrary to the Precambrian earth-life system dominated by microbial life. However, understanding Cambrian earth-life system evolution is hampered by regional and global stratigraphic correlations due to an incomplete chronostratigraphy and consequent absence of a highresolution timescale. Here we briefly review the historical narrative of the present international chronostratigraphic framework of the Cambrian System and summarize recent advances and problems of the undefined Cambrian stage GSSPs, in particular we challenge the global correlation of the GSSP for the Cambrian base, in addition to Cambrian chemostratigraphy and geochronology. Based on the recent advances of the international Cambrian chronostratigraphy, revisions to the Cambrian chronostratigraphy of China, which are largely based on the stratigraphic record of South China, are suggested, and the Xiaotanian Stage is newly proposed for the Cambrian Stage 2 of China. We further summarize the integrative stratigraphy of South China, North China and Tarim platforms respectively with an emphasis on the facies variations of the Precambrian-Cambrian boundary successions and problems for identification of the Cambrian base in the different facies and areas of China. Moreover, we discuss stratigraphic complications that are introduced by poorly fossiliferous dolomite successions in the upper Cambrian System which are widespread in South China, North China and Tarim platforms.