板块俯冲带岩浆作用过程的研究

综合分析了板块俯冲带岩浆活动的物质来源、岩浆上涌直至喷出的地球化学过程以及与这些过程相对应的时间尺度等研究的进展,指出了目前研究中存在的主要问题,并建议我国在该领域开展相关的研究中应:1)首先利用独有的地理优势,以处于弧后扩张作用早期的冲绳海槽为研究对象,开展相关的调查与研究;2)积极引进先进的技术手段;3)通过加强国际合作,积极参与国际合作项目,拓展研究领域.     

2020年7月西北太平洋和南海“空台”环流特征分析

2020年7月西北太平洋和南海出现了史无前例的“空台”事件。利用NCEP再分析数据集、中国气象局（CMA）台风最佳路径等资料研究了此次“空台”现象的大尺度环流背景及动力和热力学特征。使用台风潜在生成指数（DGPI）分析发现2020年7月大尺度环流背景不利于台风生成,环流系统的异常通过影响对流层垂直风切变和垂直运动限制了台风的活动。2020年7月马斯克林高压较常年明显偏西偏弱,导致索马里急流强度减弱,越赤道气流不活跃,菲律宾以东洋面和南海海域盛行一致的偏东气流,历史同期活跃在该区域的季风槽无法建立,从而不利于热带扰动的生成。北半球极涡主体偏向西半球一侧,影响东半球冷空气势力较弱,副热带高压位置偏西;南亚高压较历史同期偏强且偏东,其东侧强盛的偏东气流将洋中槽截断,在西北太平洋区域出现反气旋性环流,该区域下沉气流增强,导致副热带高压强度增强,对流层中层强烈的下沉气流抑制了台风的生成和发展。此外,受中高层环流系统异常的影响,7月菲律宾吕宋岛以东洋面和南海地区环境垂直风切变较常年偏高2～4 m/s,南海部分海域偏高达4～8 m/s,同时该区域内异常偏强的下沉气流导致对流层低层相对湿度偏低,大气层...     

粤东柘林湾表层沉积物中的多环芳烃

近岸海域是绝大数污染物的最终归宿,其中多环芳烃(PAHs)的污染目前已成为国内外环境问题的焦点之一[1~3].20世纪80年代以来,国内外对河口湾、港湾、近岸海域等海洋环境中PAHs的含量、组成、分布、归趋及来源等做了大量的调查[4~15].比如,中国科学院广州地化所对珠三角水域和厦门大学对厦门港一带均做了大量的工作,结果发现表层沉积物中16种优控PAHs总量在珠江口达到156~9220 ng/g,闽江口为175~817ng/g,厦门西港则在196~675 ng/g之间,证明我国东南沿海主要河口及港湾沉积物中的PAHs污染已经达到中等水平[13~15].     

Newly discovered hydrothermal fields along the ultraslow-spreading Southwest Indian Ridge around 63°E

The ultraslow-spreading Southwest Indian Ridge(SWIR) to the east of the Melville fracture zone is characterized by very low melt supply and intensive tectonic activity. Due to its weak thermal budget and extremely slow spreading rate, the easternmost SWIR was considered to be devoid of hydrothermal activity until the discovery of the inactive Mt. Jourdanne hydrothermal field(27°51′S, 63°56′E) in 1998. During the COMRA DY115-20 cruise in2009, two additional hydrothermal fields(i.e., the Tiancheng(27°51′S, 63°55′E) and Tianzuo(27°57′S, 63°32′E)fields) were discovered. Further detailed investigations of these two hydrothermal sites were conducted by Chinese manned submersible Jiaolong in 2014–2015. The Tiancheng filed can be characterized as a lowtemperature(up to 13.2°C) diffuse flow hydrothermal field, and is hosted by fractured basalts with hydrothermal fauna widespread on the seafloor. The Tianzuo hydrothermal field is an inactive sulfide field, which is hosted by ultramafic rocks and controlled by detachment fault. The discovery of the three hydrothermal fields around Segment #11 which receives more melt than the regional average, provided evidence for local enhanced magmatism providing heat source to drive hydrothermal circulation. We further imply that hydrothermal activity and sulfide deposits may be rather promising along the easternmost SWIR.     

Late Pan-African magmatism and crustal development in northeastern Egypt

The voluminous Pan-African calc-alkaline granitic suite of the Ras Gharib crustal segment in northeastern Eygpt provides a typical example of orogenic magmatism. The 552 ± 7 Ma-old granodiorite–adamellite and leucogranite suite is compositionally broad (58 to 77 wt.% SiO₂) and exhibits calc-alkaline geochemical trends and trace-element characteristics typical of the volcanic-arc granites. The rocks contain oligoclase, albite, K-feldspar, calcic amphibole, biotite, titanite, zircon, and magnetite. The suite exhibits typical features characteristic of I-type granites. We contend that the magma was formed by partial melting of a modified oceanic crust at an active continental margin during the late stage of the Pan-African orogeny. The process may have involved assimilation of Early Pan-African dioritic country rocks. The more felsic units were produced by progressive fractionation of that magma. The petrological–geochemical evidence suggest that the Pan-African crust in northeastern Egypt did not develop in an extensional tectonic regime, as proposed recently.     

Minimal cut-based recursive decomposition algorithm for seismic reliability evaluation of lifeline networks

In this paper, a new probabilistic analytical approach, the minimal cut-based recursive decomposition algorithm (MCRDA), is presented to evaluate the seismic reliability of large-scale lifeline systems. Based on the minimal cut searching algorithm, the approach calculates the disjoint minimal cuts one by one using the basic procedure of the recursive decomposition method. At the same time, the process obtains the disjoint minimal paths of the system. In order to improve the computation efficiency, probabilistic inequality is used to calculate a solution that satisfies the prescribed error bound. A series of case studies show that MCRDA converges rapidly when the edges of the systems have low reliabilities. Therefore, the approach can be used to evaluate large-scale lifeline systems subjected to strong seismic wave excitation.     

Interpretation of aeromagnetic anomalies over part of Southeastern Nigeria using three-dimensional Hilbert transformation

We present the results of the application of three-dimensional Hilbert transformation to the analysis of airborne total field magnetic anomalies over part of Southeastern Nigeria. This study not only substantiates the usefulness of 3-D Hilbert transforms in the interpretation of magnetic anomaly maps but also more clearly delineates the structural pattern of the area, of study. Results from the previous study are discussed in relation to the results of previous geological and geophysical studies of the area.     

资源最优空间配置的系统经济理论研究

本文不仅研究了包括生产、消费、资源的空间配置和空间位置差异的一般经济均衡条件,而且还以大系统多级递阶控制原理,建立了统一协调的系统经济数学模型。该模型深刻地揭示了生产、消费、资源的空间配置与空间位置差异之间的相互关系,同时也是区位论的一种理论模式。     

罗锅沟大爆破技术

以罗锅沟大爆破为例，介绍了洞室大爆破的施工组织，并着重问述了在进行技术设计时，应注意以下几点：（１）药室的布置及爆破参数的确定；（２）起爆网路的设计；（３）施工设计；（４）安全校核及安全措施。     

VENTILATION FLOW IN A BAROCLINIC VORTEX RELATED TO TROPICAL CYCLONE MOTION*

The tropical cyclone motion is numerically simulated with a quasi-geostrophic baroclinic model.The flow field of a tropical cyclone is decomposed into its axisymmetric and asymmetric components.The relation between the ventilation flow vector and the motion vector of the tropical cyclone is investigated.The results of numerical experiments indicate:(1) There are both large-scale beta gyres and small-scale gyres in the asyrnmetric flow field.(2) The interaction between small-scale gyres and large-scale beta gyres leads to the oscillation of translation speed and translation direction for the tropical cyclone.(3) There are the large deviations between the ventilation flow vector calculated by means of Fiorino and Elsberry's method and the motion vector of tropical cyclone.(4) The ventilation flow vector computed using the improved method closely correlates with the motion vector of the tropical cyclone.