传统时期太湖流域的渔民及其生计

传统时期太湖流域的渔民群体分为陆上定居的兼业渔民(仍属农民身份)和水上流动的专业渔民,其生产与生活方式因水环境和鱼资源的分布而存在区域差异。太湖周边低地湖荡区的兼业渔民从事捕鱼的环境支持度和资源便利程度较高,渔业在农村副业序列中占有重要地位。东部河网地区水鱼资源欠丰,捕鱼技术简单,农民捕鱼生产的季节性和流动性较大。太湖上流动捕鱼的专业渔民生产技术高,具有规模化和互助性,构成自然捕捞商品鱼生产的主力大军。流动于东部内河上的专业渔民以单家独户生产为主,产量低收入少,缺乏互助合作。各类渔民共同具有的流动性和人口来源的复杂性,使其成为社会安全管理的重灾区,也是促成20世纪60,70年代政府彻底实施渔民上岸定居的重要原因。     

应用碳、氦、氩同位素探讨济阳拗陷二氧化碳气成因

应用碳、氦、氩同位素和气体组分指标 ,以及流体包裹体测定等手段 ,结合济阳拗陷基本地质条件 ,提出二氧化碳气藏的二氧化碳气主要以幔源成因为主。     

盆地形成及成矿与地幔流体间的成因联系

文中共讨论以下5个问题:(1)盆地起源于幔壳溃变和膨隆,后者是地幔流体(超临界态(>375℃)HACONS流体,简称幔汁)上涌、渗入、交代、富化、致熔的产物。地幔流体造成油气盆地深部的高热流、异常超高压、伊利水云母化、硅化和地层有机碳的加氢成油作用。(2)盆地成矿可分两大阶段,先是沉积时的同生成矿;地层沉积后还有众多的后生成矿。两者组成“盆地矿套”(杜乐天,2002)。成矿无论同生还是后生,其分布均受断裂控制,都和地幔流体活动有关。(3)黑色页岩的实质是碳-硅-泥三元岩系,和热液成矿中的碳酸盐-硅质-泥质蚀变三元完全相当。此类岩系中总是有几十种亲壳亲幔亲气元素的特殊富集。奇异的是,石油、油页岩、沥青及砂岩型铀矿彼此有完全类似的继承性元素特殊富集。此等元素群不可能都是来自盆地之外蚀源区岩体的风化。研究证明,相当多的元素是地幔流体携带上来的。(4)盆地地层中广泛发育由地幔流体衍生的热液作用。(5)盆地实质上是气盆,全盆地排气。许多气田是地幔流体排气形成的。沙漠(原地型)和天然气田的共生很值得注意,两者皆源于地球强烈排气,导致地下和大气增温,过度蒸发,不易降雨,长期干旱而形成沙漠。     

Differences Between Mode I and Mode II Crack Propagation

Although mode I and mode II crack propagation show many similarities, in particular when analysed by linear elastic fracture mechanics, they differ significantly in the micro-structural behaviour. These differences, which are clearly noticeable in the fracture surface morphology, lead to fundamental differences in the macroscopic behaviour. Thus, mode II crack expansion under remote loading, appears to obey micro-structural scaling laws, implying that the dimensions of the process region stay essentially constant during crack expansion, rather than increasing with crack length. Therefore, expanding mode II cracks can almost reach the Rayleigh velocity, and actually also intersonic velocities. An expanding mode I crack, on the other hand, seems to obey continuum scaling laws, implying that the dimensions of the process region increase in proportion to crack length, leading to self-similar crack expansion at a velocity significantly below the Rayleigh speed and dependent on the remote load.     

华北地块南缘花山、五丈山岩体LA-ICP-MS锆石U-Pb年龄、地球化学特征及成因

花山复式岩体位于华北地块南缘,采用LA-ICP-MS技术测得复式岩体中的中细粒似斑状黑云二长花岗岩的锆石U-Pb年龄为128±1Ma,此年龄被解释为成岩年龄。该岩体及邻近的五丈山岩体中花岗岩具有高硅、富碱特征,为准铝-弱过铝质高钾钙碱性系列;在稀土和微量元素上,富集LREE、Rb、Ba、K、Sr等大离子亲石元素,亏损HREE、Zr、Hf、Ta、Nb、P、Ti等高场强元素,总体上Eu异常不明显,显示出I-A过渡型花岗岩的特征。锆石Lu-Hf同位素组成表明,花山花岗岩的εHf(t)主要变化于-25.8~-19.6之间,tDM2为2.81~2.43Ga,显示源区物质以古老的壳源物质为主,有年轻组分的参与。与岩体外围多金属成矿年龄的对比分析发现,外围金、钼矿床与花山复式岩体的年龄一致,比五丈山岩体晚20~25Ma,表明金、钼矿的形成与花山岩体在时空上联系密切,该岩体可能为成矿提供了热源。     

B-polarization induction in two thin half-sheets coupled to the mantle by a conducting crust—II. Solution by the mode-matching method, the fields above the conductors, and example results

The mode-matching method is used to obtain an exact analytical solution to the problem of B -polarization induction in two adjacent thin half-sheets, lying on a conducting layer that is terminated by a perfect conductor at finite depth. These components of the model represent, respectively, the Earth's conducting surface layers, crust, and mantle. In dimensionless variables, the model has three independent parameters, these being the two thin-sheet conductances and the layer thickness. The mode-matching solution obtained in this paper is shown to be identical lo that derived via the Wiener-Hopf method in a companion paper (Dawson 1996), and so provides additional verification of that solution. As was shown in the companion paper, the solution for the present model contains, as special limiting cases, those for three models considered earlier by various authors. The second part of the present paper addresses the solutions for the electric fields in the non-conducting half-space above the conductors, which represents the atmosphere. In the final part, sample numerical calculations are presented to illustrate the solution.     

The influence of air–sea–ice interactions on an anomalous phytoplankton bloom in the Indian Ocean sector of the Antarctic Zone of the Southern Ocean during the austral summer, 2011

An anomalous phytoplankton bloom was recorded in the Indian Ocean sector of the Antarctic Zone (AZ) of the Southern Ocean (SO) during the austral summer, 2011. Possible mechanisms for the triggering of such a large bloom were analyzed with the help of in situ and satellite data. The bloom, which formed in January 2011, intensified during February and weakened by March. High surface chlorophyll (Chl) concentrations (0.76 mg m⁻³) were observed in the area of the bloom (60°S, 47°E) with a Deep Chlorophyll Maximum (DCM) of 1.15 mg m⁻³ at a depth of 40–60 m. During 2011, both the concentration and spatial extent of sea ice were high on the western side of the bloom, between 0°E and 40°E, and enhanced freshwater influx was observed in the study area as a result of melting ice. A positive Southern Annular Mode (SAM) (with a resultant northward horizontal advection) and an intense La Niña during 2010–2011 are possible reasons for the high sea-ice concentrations. The enhanced Chl a observed in the study region, which can be attributed to the phytoplankton bloom, likely resulted from the influx of nutrient-laden freshwater derived from melting sea ice.     

广东英德市碳酸盐岩地热田地温场特征和成因

广东省英德市横石塘地区的地热田属于碳酸盐岩型地热资源。文章根据钻孔测温资料,结合区域地质资料,分析了该地热田的地温场特征、埋藏条件、补径排条件等。该地热田主要热储层为泥盆―石炭系碳酸盐岩,热水径流特征和地温场特征受吴川―四会深断裂带的一系列构造控制。测温曲线显示：地温场形态呈不规则长椭圆形,长轴方向近北西向,可以推断地温场变化与岩石的断裂、裂隙和溶蚀程度有关。本区无附加型热源,深循环为该区热水的主要形成原因。