贵州碳酸盐岩红色风化壳次生石英的裂变径迹测年研究

贵州位于青藏高原东南缘,由于缺乏沉积记录其新生代的地质演化历史还不很明晰,而广泛分布于云贵高原的碳酸盐岩红色风化壳可能蕴涵着重要的地质演化信息.本文对贵州多个原位碳酸盐岩红色风化壳中产出的晶体形态较好的石英进行了裂变径迹方法测年.结果显示,石英的裂变径迹年龄数据呈现出较大的变化范围,从 1 Ma到 25 Ma,且远远地小于其三叠纪和寒武纪的母岩年龄;结合贵州 25 Ma到 1 Ma的区域地质演化历史,裂变径迹年龄值可以排除石英来源于母岩碎屑、成岩过程的次生形成以及火山活动产生的热水沉淀或交代形成的可能性,而只能推断为该晶体形态较好的石英于碳酸盐岩风化作用产生的富硅流体中沉淀形成;各剖面石英的年龄值与新生代的青藏高原夷平期、华南红土期、贵州构造稳定期乃至世界范围内的风化气候期有着良好的对应关系,说明次生石英裂变径迹测年具有很好的可行性和可靠性.     

我国天文台及潜在台址所在地区Fried参数γ0的计算与统计分析

用1986-1995年的10年探空气象资料，在塔塔尔斯基模式下，计算了我国天语言台及候选台址所在的10个地区的Fried参数r0。给出了地面、900米、1500米、3000米、5000米各度上的r0年平均值。在3000米高度上冬季丽江视宁度最好，夏季酒泉最好，均达到相应季节定日4301米高度上视宁度水平。     

半干旱半湿润地区洪水预报模型适用性研究

针对半干旱半湿润地区的流域特性和产汇流特点,比较了河北雨洪模型和新安江模型的模型原理和模型特性,以滦河支流老牛河流域为例,开展了洪水预报适用性研究。结果表明,河北雨洪模型的预报精度较高,更适用于半干旱半湿润地区的洪水预报。     

松嫩平原哈尔滨地区地下水环境背景值分析

受自然条件及人类活动的影响,地下水环境发生了较大的变化,地下水污染问题日益引起广泛的关注。正确确定背景值对地下水污染评价十分重要。以收集的松嫩平原哈尔滨地区150余组地下水水化学样品分析数据为依据,在分析区域流场、补给径流条件的基础上,选用数理统计法和经验法求取了研究区潜水和承压水地下水环境背景值,并对地下水环境背景值进行比较。结果表明:数理统计法以自然地理环境和人类长期活动的综合作用为基础,克服了经验法的不足,可较真实地反映研究区地下水背景状况;研究区内潜水中指标NO3-、Fe、Mn和承压水中指标Fe、Mn均为高背景值指标;区内地下水环境背景值与人类活动、地下水的补、径、排和沉积环境条件具有密切的关系。     

Matrix Corrections and Error Analysis in High‐Precision SIMS 18O/16O Measurements of Ca–Mg–Fe Garnet

We report technical and data treatment methods for making accurate, high‐precision measurements of ¹⁸O/¹⁶O in Ca–Mg–Fe garnet utilising the Cameca IMS 1280 multi‐collector ion microprobe. Matrix effects were similar to those shown by previous work, whereby Ca abundance is correlated with instrumental mass fractionation (IMF). After correction for this effect, there appeared to be no significant secondary effect associated with Mg/Fe²⁺ for routine operational conditions. In contrast, investigation of the IMF associated with Mn‐ or Cr‐rich garnet showed that these substitutions are significant and require a more complex calibration scheme. The Ca‐related calibration applied to low‐Cr, low‐Mn garnet was reproducible across different sample mounts and under a range of instrument settings and therefore should be applicable to similar instruments of this type. The repeatability of the measurements was often better than ± 0.2‰ (2s), a precision that is similar to the repeatability of bulk techniques. At this precision, the uncertainties due to spot‐to‐spot repeatability were at the same magnitude as those associated with matrix corrections (± 0.1–0.3‰) and the uncertainties in reference materials (± 0.1–0.2‰). Therefore, it is necessary to accurately estimate and propagate uncertainties associated with these parameters – in some cases, uncertainties in reference materials or matrix corrections dominate the uncertainty budget.     

论地壳运动的宇宙起因

本文笔者认为,宇宙事件是地壳运动的主要动力之一。与地壳运动有关的宇宙事件共有12种,其中6种为正常事件,它们改变地球自转速率,并进而引起跃变地壳运动;另6种为灾变事件,它们直接启动岩石圈的板块运动,并导致突变地壳运动。地质历史上,可相应地划分出12个宇宙事件构造旋回,它们各自对应着不同型式和规模的宇宙事件和地质事件。质量较大的小天体对北冰洋、太平洋、大西洋和印度洋的4次冲击,塑造了全球地幔对流和海陆分布的基本格局。     

INTEGRAL REPRESENTATIONS AND REGULARIZATIONS FOR A DIVERGENT SERIES SOLUTION OF A BEAM SUBJECTED TO SUPPORT MOTIONS

Derived herein is the integral representation solution of a Rayleigh-damped Bernoulli–Euler beam subjected to multi-support motion, which is free from calculation of a quasi-static solution, and in which the modal participation factor for support motion is formulated as a boundary modal reaction, thus making efficient calculation feasible. Three analytical methods, including (1) the quasi-static decomposition method, (2) the integral representation with the Cesàro sum technique, and (3) the integral representation in conjunction with Stokes' transformation, are presented. Two additional numerical methods of (4) the large mass FEM simulation technique and (5) large stiffness FEM simulation technique are easily incorporated into a commercial program to solve the problem. It is found that the results obtained by using these five methods are in good agreement, and that both the Cesàro sum and Stokes' transformation regularization techniques can extract the finite part of the divergent series of the integral representation. In comparison with the Mindlin method and Cesàro sum technique, Stokes' transformation is the best way because it is not only free of calculation of the quasi-static solution, but also because it can obtain the convergence rate as rapidly as the mode acceleration method can.     

Changes of the 0°C isotherm and the equilibrium line altitude in central Chile during the last quarter of the 20th century / Changements de l'isotherme 0°C et de la ligne d'équilibre des neiges dans le Chili central durant le dernier quart du 20ème siècle

Abstract

An overall retreat of glaciers has been observed in the Andes of central Chile during the last ~100 years. Precipitation is mainly of frontal origin and concentrates in winter months. Analysis of precipitation data shows a decrease until 1976, an increase thereafter north of 34°S and a decrease south of 34°S, but overall no significant trends during the last quarter of the 20th century. Analysis of radiosonde data of central Chile shows mid-tropospheric warming with an elevation increase of the 0°C isotherm of 122 ± 8 m and 200 ± 6 m in winter and summer, respectively, during the 27-year period between 1975 and 2001. The results point to a snowline elevation increase in the region during the last quarter of the 20th century and a concurrent rise of the equilibrium line altitude (ELA) and suggest that mid-troposphere warming is the main cause for glacier retreat in central Chile.     

Application of Cesàro mean and the L-curve for the deconvolution problem

In this paper, the Cesàro mean technique is applied to regularize the divergent problem which occurs in ground motion deconvolution analysis in geotechnical engineering. To deal with this ill-posed problem, we use the corner of the L-curve as the compromise point to determine the optimal order of Cesàro mean so that the high frequency content can be suppressed instead of engineering judgement using the concept of a cutoff frequency. The fractional order of Cesàro mean has been derived and used to fulfill this purpose. From the examples shown, it is found that the wave form including maximum acceleration can be accurately predicted and that both the high frequency content and divergent results can be avoided by using the proposed regularization technique.     

溧阳火山岩盆地TM遥感图像线性构造密度分析

利用１：１０万溧阳火山岩盆地ＴＭ图像线性影像解译图上线性影像的长度、方位、频度及构造可信度为基本数据,通过作线性影像方位－频度直方图、线性构造等密度图等统计分析,研究区内线性构造的优势方位、异常带的空间展布规律及各向异性,为研究区域构造格局、构造序次及其控矿关系提供依据。