2011～2012年冬季欧亚大陆低温严寒事件与平流层北极涛动异常下传的影响

利用NCEP-NCAR 再分析资料分析了2011～2012 年冬季发生在欧亚大陆的一次异常低温严寒事件的大气环流演变过程以及可能的成因。这次低温事件,主要出现在2012 年1 月下旬至2 月上旬,持续大约3 周左右,非常强的低温异常覆盖了几乎整个欧洲以及东亚的西伯利亚、蒙古国和我国东北、华北等地。这次低温事件的演变与对流层北极涛动(AO)由正位相转变为负位相的时间相匹配,意味着AO 可能发挥重要作用。进一步分析表明,前期行星波的异常上传导致平流层发生爆发性增温现象,极夜急流减弱,AO 位相首先在平流层由正变负;在2～3 周左右的时间内,平流层AO 异常信号逐渐下传,使得对流层AO 也转为负位相;随后,乌拉尔山阻塞高压异常发展,极区的冷空气不断向南爆发,先后在东亚和欧洲造成剧烈的降温,导致低温严寒事件。因此,考虑平流层环流的异常可能有助于提高欧亚大陆冬季低温严寒事件的预测能力。     

Controls on P–T–t deformation path from amphibole zonation during progressive metamorphism of basic rocks (estuary of the River Vilaine, South Brittany, France)

Abstract Edenite/tremolite and edenite/magnesio-hornblende in equilibrium with plagioclase, chlorite, epidote, quartz and vapour involve several types of reactions for which K _D can be related to T and P. Thermodynamic calculation of these equilibria leads to isopleth systems. Given knowledge of the progressive changes of end-member activities in zoned Ca–Mg amphiboles (based on microprobe analyses), it is possible to construct precise pressure–temperature–time paths ( P–T–t paths) which have been followed by metabasites during polyphase metamorphism. When applied to basic rocks from the River Vilaine area, this method allows us to construct a P–T–t path that can be compared directly to the P–T–t path constructed from interbedded acid rocks (aluminous micaschists) in the same structural unit. Through time, both basic and acid rocks underwent the same complex deformation history that can be described conveniently in the L–S fabric system of Flinn. This allows us to construct a P–T–t deformation path for this structural unit.
These paths are interpreted in terms of an under/overthrusting continental collision belt (the Hercynian belt), and represent an illustration of the time delay caused by stacking of more than two crustal units.     

关于"十五"期间浙江省国土资源开发利用与保护的措施建议

文章通过对我省土地和矿产资源开发利用的现状分析,指出了土地资源管理存在的主要问题,并提出了在"十五"期间应采取的对策和保护措施建议.     

地震属性分析在岩性气藏描述中的应用

针对鄂尔多斯盆地上古生界二叠系盒8砂岩岩性气藏非均质性强、开发前期井少、井距大、储层预测难的特点,通过地震多种属性分析,并结合井资料,利用地质统计学方法优选出对砂岩厚度、储层物性及含气性较敏感的地震波形、地震波速度变异参数和地震子波吸收系数3种属性,根据这3种地震属性的分类特征对盒8砂岩厚度和储层含气性的平面分布进行了预测和描述,划分的Ⅰ+Ⅱ类含气有利区被确定为下一步的评价区块。地震属性分析应用于非均质岩性气藏的早期描述,为评价部署和开发方案编制提供了依据。     

招平断裂带中段深部结构构造——来自地震剖面的证据

玲珑花岗岩岩基东侧的招平断裂带是胶西北矿集区的主要控矿构造之一。布设于招平断裂带中段大尹格庄矿区的地震剖面,揭示了招平断裂带中段深部的结构构造特征,地震剖面显示,玲珑岩基内部有多个类似"拱弧构造"的岩浆侵入形成的弧形界面,由此推测存在2~3期的岩浆活动。剖面显示了3期构造组合样式,第1期为以招平断裂带和宋家河断裂为组合倾向SE的铲式断裂,底部似汇入统一的构造滑脱带;第2期为倾向NW的错断了招平断裂带的反倾伸展断裂;第3期为NE向延伸以花状构造为特征的走滑断裂。前两期反映构造发育处于伸展环境,第3期显示为左行走滑。招平断裂带深部延伸存在分支复合现象,形成由2个主裂面夹持的透镜状岩片。地震反射剖面数据的获得对深刻理解该区域中生代岩浆构造演化过程和深部找矿具有重要的借鉴意义。     

砂岩型铀矿床硫化物还原富集铀的机制

砂岩型铀矿中含大量不同形态、不同阶段的黄铁矿。仅凭矿相学对黄铁矿产状及电子探针对黄铁矿形态的观察难以准确地判别成矿期、成矿前及成矿后形成的黄铁矿。而成矿期黄铁矿是铀矿床成因和形成过程的重要信息载体,对其准确识别具有特别重要的意义。以往国内外研究采用激光剥蚀电感耦合等离子体质谱(LA-MC-ICP-MS)方法分析Pb同位素,但该方法对于低含量Pb样品分析精度较低且较难获得²⁰⁴Pb数据。本文对铀矿石中的黄铁矿利用微区原位的手段进行更加精准的飞秒级质谱(fs-LA-MC-ICP-MS)的Pb同位素测试,发现大量黄铁矿存在Pb同位素异常,从中可能区分出成矿期与非成矿期的黄铁矿。经U-Th-Pb放射性衰变原理分析并结合黄铁矿矿相学特点可以发现,矿相学镜下明确是成矿期的黄铁矿,其²⁰⁶Pb/²⁰⁴Pb比正常克拉克值大十几倍甚至数十倍,²⁰⁷Pb/²⁰⁴Pb稍有异常,而²⁰⁸Pb/²⁰⁴Pb基本不变。矿相学中产状呈草莓状,以及铀矿物围绕其生长但未有穿插关系的非成矿期黄铁矿,其²⁰⁶Pb/²⁰⁴Pb正常;矿相学镜下难以确定形成阶段的、与铀矿物没有任何接触关系的黄铁矿,其Pb同位素没有明显的规律性。这些结果证明了利用Pb同位素异常来判断黄铁矿形成阶段的准确性。因此,利用黄铁矿微区原位Pb同位素差异,适当配合矿相学形态和产状观察,可较为精准地识别出成矿期黄铁矿。

     

Analyses of spring mean circulations for major and minor dust storm years in China–Mongolia area

To better understand the dust storm (hereafter DS) inducing circulation in the China–Mongolia (CM) DS activity area, the spring mean circulation features and differences on lower levels in three subregions of the CM DS area for the major- and minor-DS years have, as a whole (not partly), been analyzed, utilizing the National Centers for Environmental Prediction and the National Center for Atmospheric Research (NCEP/NCAR) reanalyzed gridded data, the observed DS frequency data in the CM area, and the composite analysis method. The main conclusions are as follows: (1) Judging from the differences in the DS-inducing systems, dust origins, paths of invading cold air, and main DS-strike areas, the whole CM DS area is roughly divided into the three subregions: the East-, Middle- and West-CM subregions (in this paper, referred to as E-, M-, and W-CM). (2) In major DSs during spring over the E-CM, the middle- and lower-level troughs or cyclones over the Japan Sea and northeastern China (NEC) dominate. The invading cold air along the northeastern (NE) or north by east (NE) path often causes the DS in the E-CM region. But nearly the opposite is true in minor DS during spring in E-CM. (3) In the major DS during spring over the M-CM region, the Mongolian troughs or cyclones are the main DS-inducing systems. The strong invading cold air along the northwestern (NW)- or north by west (Nw) path causes the DSs in the M-CM region. (4) In the major DSs during spring over the W-CM region, the South Xinjiang heat lows prevail, the intruding cold air has a western path, and creates the DSs in South Xinjiang. (5) In the past 50 years, the DSs over the M-CM region have had the most severe impact on the preceding three subregions of the CM DS area. Overall, DS activities over all of three regions of the CM area decreased in the past (particularly, over M- and W-CM regions since the mid-1980s. But there existed a short and sudden increasing in E-CM in the years 2000–2002. (6) It is circulation changes and desertification evolutions that cause the yearly and decadal changes of DS in CM area, especially the former. With the backdrop of global warming in the future, perhaps the decreased DS activities over M- and W-CM will persist for some time again, and special attention should be paid to ones over E-CM or to the individual DS events over M- and W-CM.     

解放战争时期解放区的社会救助

解放战争时期,由于战争、自然灾害、战勤等原因,解放区的难民、灾民等弱势群体问题十分严重。中国共产党在领导人民进行解放战争的同时,通过采取有计划地安置弱势群体、发放紧急赈济、防疫治病、对弱势群体进行心理干预、大力发展农业副业生产等措施,积极进行弱势群体的社会救助工作并取得了显著的成效。解放战争时期解放区的社会救助实践对当今的社会救助事业发展以及和谐社会的构建起到了很好的借鉴作用。     

山东省汛期降水的变化及其与北极海冰的关系

首先对1951～1999年山东省汛期(7～8月)降水进行了Z指数转换、小波分析和滑动t检验。发现49a来．山东省汛期降水呈明显减少的趋势。在60年代到70年代雨涝出现频繁。而在80年代到90年代以干旱多见。山东省汛期降水在1979年前后发生一次明显的变化．1979年后降水显著减少。山东省汛期降水变化有11a左右的年代际变化周期和2～3a、7a左右的年际变化周期。最后利用相关分析方法分析了山东省汛期降水与北极不同分区海冰面积的相关关系。     

Open Fissure Folds record coseismic loading and postseismic stress relaxation

Open Fissure Folds hosted by high pressure/low temperature metamorphic rocks of south Evia (Greece) are introduced, their structural and microstructural record is analysed, and a mechanical model is proposed. Open Fissure Folds are preserved as at least two parallel folded quartz–feldspar veins separated by narrow buckled rock columns. The veins originated as tensile cracks that propagated in the middle crust driven by high differential stress. Features diagnostic for Open Fissure Folds indicate that the rock columns represented the layers of high viscosity, and not the veins as consistently reported in many previous studies on folded veins. This record is taken to indicate that buckling of the rock columns initiated after arrest of the fractures and terminated prior to complete vein sealing. Accordingly, mechanical decoupling by open fissures allowed for buckling of the rock columns in response to episodic creep of the host rocks according to stress relaxation, as expected for postseismic deformation in the earthquake cycle. I propose that the parental fractures propagated in response to quasi-instantaneous coseismic loading of the middle crust. Buckling was attributed to transient postseismic creep and stress relaxation. Complete sealing of the veins occurred when stresses were largely relaxed. Each Open Fissure Fold records the stress and strain history of a single earthquake.