1978-2018年中国环境污染的时空特征——基于《人民日报》新闻报道

利用1978-2018年《人民日报》的2238条环境污染新闻报道,分析了改革开放40年间中国环境污染的时空特征,并初步探讨了其与社会经济发展的关系.通过人工判读,逐条提取新闻报道的环境污染类型、时间与地点,进而通过统计分析,研究发现:①1978-2018年中国的环境污染报道经历了3个热点时期,其中前两个时期(20世纪8...     

轴向受压矩形开孔板极限强度近似计算

针对受均匀轴向压力的矩形开孔板剩余极限强度的问题,考虑矩形板中间开圆孔和腰圆孔两种典型形状,四种边界条件下,以板的柔度系数、开孔率为主要影响参数通过大量非线性有限元数值计算分析,采用一种新的拟合方式提出了矩形开孔板轴向受压剩余极限强度的简化计算公式,新经验公式能够很好地反映开孔所导致板极限强度的衰减趋势。将所提出的经验公式计算结果分别与相应的试验结果、非线性有限元计算结果及其他经验公式计算结果进行对比分析。结果表明所提出的经验公式相比已有的经验公式计算更为准确,适用范围更广,可以用来预报不同边界条件下轴向均匀受压开孔矩形板的极限强度。     

Mechanistic Drifting Forecast Model for A Small Semi-Submersible Drifter Under Tide-Wind-Wave Conditions

Understanding the drifting motion of a small semi-submersible drifter is of vital importance regarding monitoring surface currents and the floating pollutants in coastal regions. This work addresses this issue by establishing a mechanistic drifting forecast model based on kinetic analysis. Taking tide-wind-wave into consideration, the forecast model is validated against in situ drifting experiment in the Radial Sand Ridges. Model results show good performance with respect to the measured drifting features, characterized by migrating back and forth twice a day with daily downwind displacements. Trajectory models are used to evaluate the influence of the individual hydrodynamic forcing. The tidal current is the fundamental dynamic condition in the Radial Sand Ridges and has the greatest impact on the drifting distance. However, it loses its leading position in the field of the daily displacement of the used drifter. The simulations reveal that different hydrodynamic forces dominate the daily displacement of the used drifter at different wind scales. The wave-induced mass transport has the greatest influence on the daily displacement at Beaufort wind scale 5-6; while wind drag contributes mostly at wind scale 2-4.     

Results from a detailed aeromagnetic survey across the northeast Newfoundland margin, Part II: Early opening of the North Atlantic between the British Isles and Newfoundland

Poles of rotation for the North Atlantic have been derived from the results of a new aeromagnetic survey northeast of Newfoundland. Reconstruction of the North Atlantic at anomaly 34 time shows a band of large amplitude magnetic anomalies which parallels anomaly 34 on both sides of the Atlantic from Flemish Cap and Goban Spur to the Azores-Gibraltar Fracture Zone. A group of similar anomalies has also been identified in the Bay of Biscay. North of Goban Spur and Flemish Cap, these anomalies follow the ocean-continent boundary. Poles of rotation derived for this anomaly show that it forms an isochron (100–110 m.y.) during the long Cretaceous normal polarity interval. The cause of this anomaly is not definite, but it may represent an increase in the magnetization of the crust during a limited time within the Cretaceous Magnetic Quiet Zone by a process such as replacement of thermoremanent magnetization by chemical remanent magnetization as proposed by Raymond and LaBrecque.The North Atlantic has also been reconstructed at the time of the initial opening in the region between Flemish Cap and the Charlie-Gibbs Fracture Zone, using inferred ocean-continent boundaries on the west and east sides: it has been shown that the entire region could not have saparated at one time, but that spreading between the British Isles and Newfoundland had to progress from south to north. Consequently, when active sea-floor spreading was taking place between Goban Spur and Flemish Cap (about 110 m.y.) the region to the north was still being stretched. The calculated amount of stretching as derived from the reconstructions (about 25%) agrees well with the extension of the lithosphere obtained from modelling the subsidence history of this region, and with the results of deep seismic studies. Active spreading in the north started about 100 m.y. ago.     

旋转地球上大陆板块倾斜态势的力学原理研究

根据力学原理描述了轻物体在加速流体中的运动所具有的运动特征，将此原理应用于大陆漂移，发现板块由于地球自转而成倾斜态势。倾斜着的板块产生俯冲还是仰冲决定于地幔对流，大陆向赤道漂移是由于板块受惯性离心力和对应的附加力产生的力偶使板块南倾北仰造成的板块向赤道俯冲所致。     

北冰洋浮冰区近冰层湍流通量计算方法比较

利用2003年中国第二次北极科学考察获得的北冰洋浮冰区近冰层气象要素梯度观测资料,应用空气动力学的廓线法和总体输送法以及不同的普适函数,计算分析了2003年8月23日至9月4日浮冰区近冰层的摩擦速度、感热通量和潜热通量.结果表明:Holtslag普适函数的计算结果明显优于其它普适函数,总体输送法计算的不同层次湍流通量比廓线法更能够满足近冰层的常值通量层的假设,其结果可望为进一步优化北冰洋浮冰区边界层参数化方案和提高计算精度提供重要依据.     

特提斯地球动力学

特提斯是地球显生宙期间位于北方劳亚大陆和南方冈瓦纳大陆之间的巨型海洋,它在新生代期间的闭合形成现今东西向展布的欧洲阿尔卑斯山、土耳其-伊朗高原、喜马拉雅山和青藏高原。根据演化历史,特提斯可划分为原特提斯、古特提斯和新特提斯三个阶段,分别代表早古生代、晚古生代和中生代期间的大洋。大约在500Ma左右,冈瓦纳大陆北缘发生张裂,裂解的块体向北漂移,并使其与塔里木-华北之间的原特提斯洋在420～440Ma左右关闭,产生原特提斯造山作用,与北美-西欧地区Avalonia地体与劳伦大陆之间的阿巴拉契亚-加里东造山作用基本相当。原特提斯造山带之南、早古生代即已存在的龙木错-双湖-昌宁-孟连古特提斯洋在380Ma向北俯冲,使早期闭合的康西瓦-阿尼玛卿洋重新张开,并由于弧后扩张形成金沙江-哀牢山洋。330～360Ma左右,特提斯西部大洋由于南侧非洲板块和北侧欧洲板块的碰撞而关闭,形成欧洲华力西造山带。而特提斯东段的上述三条古特提斯洋在250Ma左右基本同时关闭,华北、华南、印支等块体聚合形成华夏大陆。该大陆与冈瓦纳大陆、劳亚大陆和华力西造山带一起围限形成封闭的古特提斯残留洋,并一直到晚三叠世-早侏罗世海水才全部退出。此后,南侧冈瓦纳大陆在三叠纪晚期重新裂解形成新特提斯洋,该洋盆在新生代初期由于印度和亚洲的碰撞而关闭。原、古、新特提斯三次造山作用基本代表了中国大陆显生宙期间的地质演化历史,并在此过程中形成了特色的特提斯域金属成矿作用。广布的被动陆缘和赤道附近的古地理位置,以及后期的造山作用同时也成就了特提斯域内巨量油气资源的形成;塑就的地貌与海陆分布格局,也对当时的古气候与古环境产生了重要影响。特别是,与原、古、新特提斯洋消亡相关的三次弧岩浆活动与显生宙地球历史上三次温室地球向冰室地球的转变,在时间上高度吻合。上述演化历史同时还表明,特提斯地质演化以南侧冈瓦纳大陆不断裂解、块体向北漂移并与劳亚大陆持续聚合为特征,其动力机制主要来自俯冲板片的拖拽力,而地幔柱是否对大陆的裂解与漂移有所贡献,则有待进一步评价。     

塔里木盆地西部断层的活动性与封闭性

研究区位于塔里木盆地西部,主要跨越巴楚断隆和阿瓦提凹陷两个构造单元.自寒武纪以来,本区主要经历了三次挤压作用,形成了第一期北西向、第二期南北向和第三期北西向褶皱和断裂构造.断层活动性是断层封闭性研究的基础和关键.活动断层的主体部分是开启的,但即使是强烈活动的断层,只要在储层或生油层附近发育较多的泥岩层构成与之相接的泥岩剪切带,断层的这些部分仍然具有封闭性.断层的封闭性应该在断层活动性研究的基础上作进一步分析.塔里木盆地西部断层的活动性与封闭性研究表明,第一期北西向断层在中寒武世-泥盆纪和第三纪-第四纪、第二期南北向断层在晚二叠世和第三纪-第四纪、第三期北西向断层自老第三纪形成以来主体部分分别处于开启状态.     

断裂成因他源高压及其地质特征

开启断裂的活动造成其断开的渗透性地层之间的水动力连通 ,从而可在浅部地层产生极高超压。这种超压在形成机制、分布特征和识别标志等方面均与传统认识和讨论的类型大不相同。笔者等通过实例 ,分析了断裂成因他源高压的形成、分布及其对油气成藏的影响等。断裂连通系统中各渗透性地层内过剩压力完全一致 ,地层压力以静水压力梯度随深度增加 ;由构造应力或由地层压力为主导因素的断裂的形成对应着不同的压力形成机制、压力分布特征及演化过程 ;这类超压带之上的压力过渡带一般较薄 ,但受地层性质及超压形成后沉积速率的影响。这类高压的研究对于识别断裂活动、划分油气运聚单元、确定油气藏动力学过程、压力预测等均有重要意义。     

北秦岭早古生代海相火山岩的实验-成分与构造开合

应用精选测试样品、多种测试结合、惰性元素核实、熔融结晶实验、分解构造环境、开合定量估算等方法，对北秦岭早古生代海相火山岩进行了火山地质学、实验岩石学、岩石地球化学及构造动力学等的综合研究，提出：（１）本区是一个中部断隆、南北断陷的裂谷造山系，火山岩以寒武－奥陶纪为主，属裂隙－多中心式的互夷－布里尼型喷发；（２）玄武岩实验研究，可给新鲜岩石液相线温度、晶出矿物、晶体形态、岩交演化与后期变化等提供重要