雪峰山西侧构造演化和构造格局对区域油气成藏条件的控制

本文对雪峰造山带北西缘及其北西侧隔槽式褶皱带的区域构造演化和构造格局与油气关系进行了总结和探讨,主要认识如下:震旦纪-早古生代的被动大陆边缘盆地(Z1-O1)和前陆盆地(O2-S)背景下形成了3套主要生储盖组合。主要烃源层牛蹄塘组早奥陶世开始排烃(油)、三叠纪末排烃(气)基本结束;五峰-龙马溪组晚古生代中期开始排烃(油),白垩纪末排烃(气)基本结束。晚奥陶世后期的都匀运动形成了雪峰造山带北缘隆起和黔中隆起(为大型圈闭),中侏罗世或中三叠世以前的油气多由周边凹陷区向这两个隆起区运移、聚集,严重影响到凹陷区中生代圈闭内天然气成藏潜力和规模。受排烃历史控制,隔槽式褶皱带内中生代圈闭构造有可能形成以五峰-龙马溪组为烃源的较大规模上组合气藏;以牛蹄塘组为烃源的下组合和中组合一般难以成藏,但在黔中隆起带有可能形成次生气藏。最后,基于构造和油气演化特征,探讨了研究区油气成藏远景,并提出了油气勘探方向建议。     

Variability in the discharge of South American rivers and in climate / Variabilité des débits de rivières d'Amérique du Sud et du climat

Abstract

Changes in trend and quasi-periodicities are sought in the time series of river discharges in all major South American basins. The relationship between trends and quasi-periodicities found and climate variations on interannual and longer time scales are discussed. Consideration of multiple rivers gives insight into the geographical extent of hydrological signals and climate impacts. It is found that the streamflow of all major rivers of South America has experienced an increased trend since the early 1970s. It is suggested that this simultaneity may reflect the impact of a large-scale climate change. All the time series of river streamflows that were analysed show El Niño-like periodicities. Only for La Plata Basin do these explain a larger part of the total variance than the other quasi-periodicities. There are two other quasi-oscillations in the time series analysed: one of them with a longer period—around 17 years—and the other of about 9 years. Previous work has related these oscillations to sea-surface temperature anomalies in the Atlantic Ocean.     

华南春季降水纬向非均匀分布及异常年大气环流特征分析

对1951—2007年华南地区18站春季（3—5月）降水进行EOF分析,发现华南春季降水的空间分布具有全区一致性、东西反位相、南北反位相及东北—西南反位相等特点。第二特征向量主要反映了华南春季降水的纬向非均匀分布特征,据此将华南春季降水型分为西涝东旱型和西旱东涝型,并利用NCEP再分析资料对春季降水的纬向分布异常年的大气环流背景特征进行了研究。结果发现：在西涝东旱年,华南西北部存在海平面气压场和高度场的正异常中心,有利于冷空气的南下,而该正异常中心的南部出现负异常,华南东部及其东部海面上呈现范围较大的气压场和高度场正异常,华南西部盛行东南风异常,华南东部存在东北风距平,风场和水汽输送场在华南西部表现为异常辐合,在华南东部表现为异常辐散,因此造成了华南西部降水的偏多和东部降水的偏少。同时,850 hPa涡度场、200 hPa散度场、850 hPa垂直速度场和1000 hPa温度场也均呈现出有利于华南西部降水增多和东部降水减少的环流形势。在西旱东涝年,情况基本相反。     

太阳系外恒星行星系统的探测与研究进展

随着对外太空探索脚步的加快，人类开始对与太阳系具有相似结构的恒星行星系统越来越感兴趣，因为它们有可能也拥有智慧生命。简单介绍了目前地外恒星行星系统的探测情况，分析了现在比较常用的几种探测方法的可行性和适用范围，重点讨论了利用视向速度法得到的结果及其意义。近年来，各种探索地外行星的小卫星的升空以及探测技术的进步使得大批高质量数据获得成为可能。可以预见，在未来几年内，地外恒星行星系统的探索将会进入一个蓬勃发展阶段。     

The Eddington Mission

The Eddington mission was given full approval by the European Space Agency on the 23rd May 2002, with launch scheduled for 2007/8. Its science objectives are stellar evolution and asteroseismology, and planet finding. In its current design it consists of 4 × 60 cm folded Schmidt telescopes, each with 6^o × 6^o field of view and its own CCD array camera. Eddington will spend 2 years primarily devoted to asteroseismology with 1–3 months on different target fields monitoring up to 50,000 stars per field, and 3 years continuously on a single field monitoring upwards of 100,000 stars for planet searching. The asteroseismic goal is to be able to detect oscillations frequencies of stars with a precision 0.1–0.3 μHz, to probe their interior structure and the study the physical processes that govern their evolution. This revised version was published online in August 2006 with corrections to the Cover Date.     

俄罗斯阿尔丹地块南部辉长-斜长岩杂岩体的构造-物质组分特点及其演化

Ｋａｌａｒｓｋｙ岩体是沿阿尔丹南部边缘分布的规模巨大的ＤｊｕｇｄｊｕｒＫａｌａｒｓｋｙ辉长－斜长岩岩带的一部分。本文研究了代表典型地球早期（前寒武纪）发展史、在行星水准上发育的这个特殊杂岩体的构造－物质组分、形成的阶段性及其继后构造演化。辉长－斜长岩杂岩体产于前寒武纪克拉通化地块交接处及其褶皱的流动性较高的框架中。该杂岩体由两个岩浆岩共生组合组成：硅铝质（斜长岩及辉长－斜长岩）及镁铁质（基性－超基性岩）。体积上前者明显小于后者。这两个岩石共生组合的锶同位素比值都特别低,说明其原始岩浆的地幔属性,是在一个相对宁静的背景中在早期分异出来的产物。辉长－斜长岩杂岩体的演化明显分３个阶段：早期是圈闭结晶岩并将其极度加热的阶段,是庞大的具对称构造的地块的形成阶段;中期是地块的最终固结阶段,在此期间发生了褶皱变形,是高压变质作用的初期阶段;晚期是发生刚性变形,形成辉长－斜长杂岩岩体的岩浆岩岩墙群、链状构造及雁行构造,并发生最大高压变质作用的阶段。文中对与辉长－斜长岩杂岩体共生的似榴辉岩也进行了探讨。     

Simulation of orthogonal horizontal components of near‐fault ground motion for specified earthquake source and site characteristics

A procedure to generate horizontal pairs of synthetic near‐fault ground motion components for specified earthquake source and site characteristics is presented. Some near‐fault ground motions contain a forward directivity pulse; others do not, even when the conditions for such a pulse are favorable. The proposed procedure generates pulse‐like and non‐pulse‐like motions in appropriate proportions. We use our recent stochastic models of pulse‐like and non‐pulse‐like near‐fault ground motions that are formulated in terms of physically meaningful parameters. The parameters of these models are fitted to databases of recorded pulse‐like and non‐pulse‐like motions. Using these empirical “observations,” predictive relations are developed for the model parameters in terms of the earthquake source and site characteristics (type of faulting, earthquake magnitude, depth to top of rupture plane, source‐to‐site distance, site characteristics, and directivity parameters). The correlation coefficients between the model parameters are also estimated. For a given earthquake scenario, the probability of occurrence of a directivity pulse is first computed; pulse‐like and non‐pulse‐like motions are then simulated according to the predicted proportions using the empirical predictive models. The resulting time series are realistic and reproduce important features of recorded near‐fault ground motions, including the natural variability. Moreover, the statistics of their elastic response spectra agree with those of the NGA‐West2 dataset, with the additional feature of distinguishing between pulse‐like and non‐pulse‐like cases and between forward and backward directivity scenarios. The synthetic motions can be used in addition to or in place of recorded motions in performance‐based earthquake engineering, particularly when recorded motions are scarce.     

“农业专家决策支撑系统”的原理和方法

本文在总结多年的研究与实践经验基础上,提出了“农业专家决策支撑系统”的基本原理与方法。这类系统的设计目标是帮助基层领导提出农业结构的优化方案,提出农林牧渔与农产品加工业的协调发展战略,并在结构优化基础上制定农业年度生产计划和长远发展规划,提高农业开发投资(资金、物资、运输和仓储等)和农业布局决策的科学水平。开发这类系统的关键技术包括:基于预测模型的农业发展规划/计划的计算机模拟方法,农业结构优化多标准评价模型,农业投资决策评估模型,农业专家知识获取和知识库建立方法,农业运输和仓储系统分析和发展战略决策方法,决策支持系统和专家系统的用户界面设计中的对弈策略与可视化技术,农业资源与环境信息管理中的ＧＩＳ与 Ｗｅｂ ＧＩＳ开发、应用技术,数据库共享服务与农村经济发展动态分析中的统计分析与制表和地图制作、报表联合应用技术,综合性系统的集成技术等。     

Dredge petrology of the boninite‐ and adakite‐bearing Hahajima Seamount of the Ogasawara (Bonin) forearc: An ophiolite or a serpentinite seamount?§

Abstract During the Hakuho‐Maru KH03‐3 cruise and the Tansei‐Maru KT04‐28 cruise, more than 1000 rock samples were dredged from several localities over the Hahajima Seamount, a northwest–southeast elongated, rectangular massif, 60 km × 30 km in size, with a flat top approximately 1100 m deep. The rocks included almost every lithology commonly observed among the on‐land ophiolite outcrops. Volcanic rocks included mid‐oceanic ridge basalt (MORB)‐like tholeiitic basalt and dolerite, calc‐alkaline basalt and andesite, boninite, high‐Mg adakitic andesite, dacite, and minor rhyolite. Gabbroic rocks included troctolite, olivine gabbro, olivine gabbronorite (with inverted pigeonite), gabbro, gabbronorite, norite, and hornblende gabbro, and showed both MORB‐type and island arc‐type mineralogies. Ultramafic rocks were mainly depleted mantle harzburgite (spinel Cr? 50–80) and its serpentinized varieties, with some cumulate dunite, wehrlite and pyroxenites. This rock assemblage suggests a supra‐subduction zone origin for the Hahajima Seamount. Compilation of the available dredge data indicated that the ultramafic rocks occur in the two northeast–southwest‐oriented belts on the seamount, where serpentinite breccia and gabbro breccia have also developed, but the other areas are free from ultramafic rocks. Although many conical serpentinite seamounts 10 km in size are aligned along the Izu–Ogasawara (Bonin)–Mariana forearc, the Hahajima Seamount may be better interpreted as a fault‐bounded, uplifted massif composed of ophiolitic thrust sheets, resembling the Izki block of the Oman ophiolite in its shape and size. The ubiquitous roundness of the dredged rocks and their thin Mn coating (<2 mm) suggest that the Hahajima Seamount was uplifted above sealevel and wave‐eroded, like the present Macquarie Is., a rare example of ophiolite exposure in an oceanic setting. The Ogasawara Plateau on the Pacific Plate is adjacent to the east of the Hahajima Seamount, and collision and subduction of the plateau may have caused uplift of the forearc ophiolite body.