桑干地区高压麻粒岩中石榴石和斜长石的连续激光探针~(40)Ar~-~(39)Ar等时年龄及其地质意义

采用微区激光探针４０Ａｒ－３９Ａｒ定年方法, 对华北桑干地区高压基性麻粒岩中变质石榴石和斜长石直接进行了原位微区年代测定。石榴石变斑晶是高压麻粒岩相变质作用形成的矿物,石榴石周围后成合晶反应边组合中的斜长石是石榴石减压分解的产物。石榴石斑晶的４０Ａｒ－３９Ａｒ等时线年龄为２５１０ Ｍａ, 证明高压变质作用发生在太古宙末。斜长石４０Ａｒ－３９Ａｒ等时线年龄为１９６８Ｍａ, 代表石榴石在中压麻粒岩相条件下分解的时代。它们之间年龄相差大于５００Ｍａ, 说明高压麻粒岩可能没有经历近等温减压的ＰＴ轨迹。后成合晶组合很可能代表中压麻粒岩相变质作用的叠加。这一结果对探讨华北克拉通桑干地区早期地壳的构造演化具有重要意义。     

结合序贯指示模拟的贝叶斯高斯混合线性反演

高斯混合模型(Gaussian Mixture Model, GMM)可以用来描述储层性质的多峰分布特性,多峰特性主要是由于它们在不同离散变量内的变化而引起的.在高斯混合模型中,高斯分量的权值代表离散变量的概率.然而,基于高斯混合模型的贝叶斯线性反演可能会对某些点的离散变量错误地分类,进而影响连续变量的反演结果,尤其存在强噪声的时候.在本文中,我们考虑了离散变量的空间变化性,并将高斯混合模型与序贯指示模拟(Sequential Indicator Simulation, SIS)相结合来确定离散变量的后验条件权值,形成了结合序贯指示模拟的贝叶斯高斯混合线性反演方法.该方法能够准确地对离散变量进行归类,且具有良好的抗噪性.通过模型试算,我们证明了这种方法的可行性,并在实际资料中取得了较好的结果.     

Characteristics of Carbonate Reservoir and Its Forming Conditions in Continental Lake Basin of China

For decades of exploration, geologists have made great achievements in the exploration of lacustrine carbonate rocks. By dissecting four typical cases of lacustrine carbonate rocks, such as Lucaogou Formation of Permian in Junggar Basin, Da'anzhai Section of Jurassic in Sichuan Basin, Cretaceous in Yin'e Basin and Oligocene in Qaidam Basin, the reservoir characteristics, hydrocarbon generating capacity and reservoir forming model of source rocks were analyzed. The results show that: \mathrm{①} Lacustrine carbonate reservoirs are generally dense, with nano-micron reservoir space as the main reservoir space, including dolomite intergranular pore, organism cavity and accumulation pore, micro-fracture system and its corrosion expansion pore. Saline environment is beneficial to dolomitization and can improve the reservoir capacity of lacustrine carbonate rocks, but most of the permeability is less than 0.1 mD. \mathrm{②} Lacustrine carbonate rocks have not only reservoir capacity, but also can be used as source rocks. The abundance of organic matter is not high and the maturity is generally low. However, dispersed soluble organic matter in source rocks can generate and expel hydrocarbons in large quantities at low maturity stage, which has high liquid hydrocarbon yield. \mathrm{③} Oil and gas reservoirs are characterized by "high initial production, large reduction of production and long-term low and stable production", and are typical "fracture-pore" reservoirs. Fracture networks provide migration pathways in the process of primary migration and accumulation of oil and gas in geological history and oil and gas exploitation nowadays. \mathrm{④} Oil and gas reservoirs are "continuous" unconventional reservoirs, which often form regional oil and gas field groups together with conventional reservoirs in adjacent areas. The research results lay a theoretical foundation for re-evaluating the exploration potential of lacustrine carbonate rocks.     

全球Argo实时海洋观测网建设及应用进展

为了使各国政府、部门管理人员和科技工作者了解国际Argo计划的实施进展,以及帮助广大民众认识实施Argo计划的重要性和已经取得的初步成果,国际Argo信息中心、国际Argo科学组和国际Argo资料管理组联合编写了一本科普宣传册,题为“Argo,一个观测实时海洋的剖面浮标网”,经翻译、整理成文,以帮助国内读者深入了解和认识这一新世纪的重大国际观测计划。文章从陈述开展海洋观测的重要性和实施Argo计划的必要性着手,系统介绍了全球Argo实时海洋观测网建设的现状和Argo资料应用研究所取得的初步成果,以及Argo计划的发展前景等。     

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???????вο???(CORS)????????????GPS???????????λ(RTK)??????????GPS??????λ?????????????? ??λ???????????????????????????????????????????е?Delaunay?????????????????????CORS????????????????????????????????????????????????ο??????????????????????????????????????????Ч???????????     

弹塑性连接梁在双薄壁高墩连续刚构桥中的应用

针对罕遇地震中弹塑性杆件塑性变形而耗能的现象,探讨了在双薄壁高墩连续刚构桥中设置弹塑性连接梁的减震方案。分别计算了是否设置弹塑性连接梁的两个桥式,比较了在大震作用下墩柱的弯矩、剪力、位移变化情况。结果显示若设置连接梁,墩柱弯矩幅值在强震中下降幅度较大,剪力有所增加而位移幅值变化不明显。     

2005年7月清江流域一次连续暴雨的中尺度分析

利用气象卫星、多普勒雷达及常规气象资料,对2005年7月8～10日清江流域连续暴雨过程进行综合分析。结果表明:(1)高低空急流的优势配置、高空急流右侧强辐散场的存在,副热带高压稳定于我国东南沿海,为此次暴雨提供了有利的大尺度环境背景;(2)雨团滞留和经过区域正是暴雨发生区域;(3)低层垂直风切变可使回波加强而产生强降水;(4)雷达回波中“逆风区”对于暴雨识别及暴雨落区预报具有很好的指示性。     

基于连续小波变换的大地电磁信号谱估计方法

在基于连续小波变换的大地电磁信号谱估计方法中 ,通过引入整体平均、小波系数收缩和显著性检验等统计技术 ,以提高谱估计的精度 .文中同时讨论了连续小波变换中各种参数的选取问题 ,给出了Morlet小波函数中尺度与傅里叶频率之间转换的经验公式 ,并给出了谱估计的具体算法 .结果表明 ,本文方法可有效压制较强的白噪声和局部相关噪声 .与FFT谱估计方法相比 ,该方法大大降低了对信号记录长度的要求 ,因而对大地电磁信号的处理有实际意义 .     

Continuous chemical monitoring of volcanic gas in Izu-Oshima volcano, Japan

A new continuous monitoring system has been developed for the measurement of volcanic gas from the steam well located 3 km north from the summit of Izu-Oshima volcano, Japan. After removing the water vapor using three sequential dehydration methods, CO₂ and SO₂ contents are measured using IR sensors, and O₂ and H₂ using a zirconia sensor and a semiconductor sensor, respectively. This system has been in operation without any significant trouble for 3 years.The dehydrated volcanic gas from the well consists of a mixture of CO₂, O₂ and N₂. A decreasing trend of the CO₂ content was observed from 1995 to 1998 together with a decrease of volcanic activity. Seasonal changes have also been observed in CO₂ and O₂ contents, CO₂ being higher and O₂ lower in summer, which suggests larger contribution of magmatic components in summer. While changes in short-term variation in CO₂ and O₂ are influenced by atmospheric pressure changes; the CO₂ content correlates inversely with atmospheric pressure unlike O₂ with some hours delay. In contrast, the H₂ content increased intermittently up to 1200 ppm one to several hours after a sudden drop in the atmospheric pressure and without any apparent correlation with seasonal changes.This system allows us to study temporal variation in chemical composition of volcanic gas during quiescent periods of volcanic activity of Izu-Oshima volcano, and might help us detect anomalous changes before future eruptive events.     

Adaptive filtering of continuous GPS results

 An adaptive finite-duration impulse response filter, based on a least-mean-square algorithm, has been used to mitigate multipath effects, and to derive tectonic and fault movement signals from continuous global positioning system (CGPS) data. By applying the filter on both pseudo-range and carrier-phase multipath sequences from CGPS observations on consecutive days, multipath models have been reliably derived. The standard deviations of residual time series are reduced to about one-quarter on pseudo-range and to about one-half on carrier phase. The adaptive filter is then used to process baseline solutions from a five-station array. Tectonic and fault movements have been resolved, which are in good agreement with previous studies involving many more CGPS stations. Received: 11 February 2000 / Accepted: 28 June 2000