Highly polarized Type III microwave bursts on 15 April 1998

A group of type III bursts observed with the 2.6–3.8 GHz spectrometer of National Astronomical Observatory of China on 15 April 1998 is analyzed. They have the characteristics of broad bandwidth (>100 MHz), very short durations (<100 ms), high polarization degree (100%), high frequency drift rates (>1 GHz s^–1), and fast pulsations (with a period of about 100–200 ms). Their time profiles are also analysed. According to these characteristics, we suggest that these microwave type III bursts may be due to the fundamental plasma emission.     

冰雹形成机制的研究并论人工雹胚与自然雹胚的“利益竞争”防雹假说

在播撒防雹中,如何实现人工雹胚与自然雹胚的增长竞争是决定防雹效果的关键,这实质上也是雹云物理的关键课题。经过对强对流(雹)云的流场特征和相应的过冷水场配置的综合分析和数值模拟研究,发现:(1)由于雹云流场的对流性,其中必然存在着一个主上升气流区和相对于云体的水平风速零的区域,它在垂直剖面上,可呈现出一条零线,可长大成冰雹的水凝物粒子是绕零线循环运行增长的,并逐步进入主上升气流区;(2)在雹云中存在着冰雹“穴道”,它位于主上升气流区边侧及零线下的入流区,其体积约为雹云总体的6％或更小,不论自然雹胚或是人工雹胚,只要进入“穴道”都经历着循环运行增长,其轨迹是相互交叉的,因而可以实现平等“竞争”;(3)“穴道”的存在和位置由流场特征决定,运行轨迹的基本形态也由流场决定,而粒子增长率及运行路径的长短由“穴道”内的过冷水场(过冷度和量)决定。     

地块—海槽边缘带成油成气新概念

对准噶尔，塔里木等盆地沉积环境的研究表明，古生代时，中国西北区海相沉积，沉积盆地的基底是一些离散的古老结晶地块，其上海水侵浸，地块之间为大洋或窄大洋的海槽，地块之间的海槽或地块与海槽过渡的边缘带盆地是油气形成的有利地带。     

豫皖交界中新生代地层特征及盆地演化

豫皖交界地段中新生代盆地位于合肥盆地的南缘。该区中新生界划分方案不一。通过超覆不整合的厘定及区域对比将其自下而上划分为中侏罗统三尖铺组、凤凰台组，上侏罗统金刚台组，下白垩统段集组、陈棚组，第三系戚家桥组和第四系。中新生界沉积物以陆相红色类磨拉石建造和陆相火山碎屑岩建造为主，陆相红色类磨拉石的建造分析表明其形成于洪积扇和扇前河湖环境，碎屑来源是沉积区南侧的大别隆起和向北逆冲的浅变质岩带。其盆地类型为复合盆地，具有由南向北、由西向东迁移的特点，而盆地的性质则发生了从前陆盆地向断陷盆地的转变     

Lipid geochemistry in a sediment core from Ruoergai Marsh deposit (Eastern Qinghai-Tibet plateau, China)

Peats in a sediment core from Ruoergai bog, which has a cold and moist plateau climate with major source input from herbaceous plants, have been studied by GC–MS in order to understand the composition and diagenetic processes of lipids in this depositional environment. Long chain components (C₂₁–C₃₅) predominate in the n-alkanes, n-alk-1-enes, n-fatty acids, n-alkan-2-ones and n-alkanols with a maximum of C₃₁, C_27, C₂₂ or C_24, C₂₃ or C₂₅ and C₂₂, respectively. A herbaceous origin for these long chain compounds is suggested, and this is supported by their stable carbon isotopic compositions. Diterpenoid hydrocarbons with abietane, pimarane and kaurane skeletons, some of which have not been reported often in modern sediments, are prominent and are derived from higher plants. Several triterpenoid ketones and alcohols with oleanane or lupane skeletons, and a series of des-A-triterpenoid hydrocarbons which have not been reported often in modern sediments are also present, and are assigned to a higher plant source. Hopanoids, including their alkanes, alkenes, ketones, alcohols and esters, are abundant and of bacterial origin. Steroid ketones and alkanols are dominated by C₂₉ homologues. C₂₈ and C₂₉ steroids are derived mainly from higher plants, whereas the C₂₇ component is assigned to a microbial source. The presence of short-chain n-alkanes with no odd-even carbon predominance, bacterially derived fatty acids (C₁₄, C₁₅, iso- and unsaturated acids), n-alkan-2-ones, des-A-triterpenoid hydrocarbons, hopanoids and some steroid ketones indicate that intense microbial reworking of the organic matter has taken place in this depositional environment. The chemical and biochemical conversions of some cyclic alkenes to alkanes, such as tricyclic diterpenoids, tetracyclic terpenoids and steroid ketones, are also evident with depth. The dominance of C₂₀ components in the diterpenoid hydrocarbons may reflect an oxidizing or reducing depositional condition.     

The UV Induced Fluorescence in Porites Coral from Hainan Island,China and Its Paleo—Environmental Implications

Porites coral in the nearshore waters off Hainan Island can give off yellowish-green fluorescence under UV laser induction.After fitting the data between rainfall and fluorescent intensity,it can be found that both appear in a simply linear equation with a correlation coefficeient of 0.78.The model equation can be used to reconstruct the rainfall in the past time by means of the determined fluorescent intensity.The correlation diagram of the determined and calculated or hindcast rainfall shows a synchronous change from 1982 to 1997.The peak positions of the variant curve are usually related to the El‘nino year.That means the drought and flood recycles are restrained to some extent by globally environmental changes.Therefore,the coral fluorescent intensity acts as a geochemical proxy for reconstructing the rainfall series in the past hundreds of years and predicting the drought-flood variant tendency in the future time.     

断层泥显微结构特征与断层滑动习性的研究

天然断层中普遍存在含有粘土矿物的断层泥，大量的实验研究和野外观察证实，不同应变速率的变形作用在断层泥中留下了特殊的显微构造特征（如褶皱、眼球状构造和膝折等）。因此，我们可以根据断层泥的变形特征，来推测变形时断层的滑动方式和次序。尽管这一方面的研究还处于探索阶段，但它可能将成为研究活断层的一个新途径。     

山门银矿卧龙矿段3号矿体物质组份及赋存状态研究

本文系统阐述了四平山门银矿物质组份及赋存状态特征。该矿床主要有用元素是银,是矿床主要的评价对象。金是主要伴生元素,具有综合利用价值。同时也查清了3号矿体中银、金等元素在矿体上的分布特征,银在矿体中自下而上,从南到北有逐渐增高的趋势,金呈上低下高,北低南高的特点。银与金重叠富集区在标高100～200m。     

湘桂粤赣区域性位场资料的数据处理及其应用

应用位场资料(△g,△T),进行数据处理和图像综合分析技术,圈定隐伏岩体,划分区域构造,提出找矿远景区,为在该区找矿预测提供新的信息.