末次间冰期以来新疆巴里坤湖蒸发盐的沉积环境记录   总被引：25，自引：9，他引：16       下载免费PDF全文

顾兆炎  赵惠敏  王振海  袁宝印 《第四纪研究》1998,18(4):328-334

沉积物岩芯的碳酸盐、石膏等蒸发盐含量和矿物组成的证据显示了新疆巴里坤湖末次间冰期以来一直是一个水位变化频繁的浅水盐湖,有时甚至为间歇式的湖泊,约在34000aB.P.前后巴里坤湖沉积相发生了显著的变化,34000aB.P.之前为泥坪-湖滨相沉积,34000aB．P．之后为成湖相沉积。尽管我们对巴里坤湖34000aB．P．前后的沉积相变难以理解,但是长期处于浅水状态的巴里坤湖沉积物中蒸发盐的含量和矿物组成仍然与气候变化密切相关。在泥坪-湖滨相形成的碳酸盐中白云石相对的增加是地表强烈蒸发的结果。以石膏为主的蒸发盐含量增加是温度和降水增加所致,而其含量减少则是冰川前进致使补给水矿化度降低造成的。这使我们获得了该区古气候变化并不服从于冰期与雨期同步模式的信息。  相似文献   

一种黄金密度的测定方法     

顾心如 《黄金地质》1998,4(4):72-75

分析了用阿基米德方法测定金块密度时影响准确度的３个因素,即不同温度下水密度的影响及其校正放置金块吊篮的影响及校正以及天平感量与测定误差间的关系。  相似文献   

山东沂水峨山口韧性剪切带糜棱岩类质量平衡分析   总被引：1，自引：0，他引：1  

顾德林  胡玲  张雪亭 《地质通报》1998,(2)

峨山口韧性剪切带糜棱岩质量分析结果表明,该剪切带是在一个开放体系非等化学背景下形成的。该带中物质组分的迁移活动,主要发生在白云母石英片岩的形成阶段,并以Ｌｏｓ（流体）、ＳｉＯ２、ＦｅＯ、Ｆｅ２Ｏ３、ＴｉＯ２、Ｋ２Ｏ大量带入,而Ｎａ２Ｏ显著带出为特征。以Ａｌ２Ｏ３守恒为限制条件,整个剪切带从原岩到白云母石英片岩的质量和体积增大约５０％。  相似文献   

南秦岭勉略古缝合带非史密斯地层和古海洋新知   总被引：12，自引：3，他引：9  

杜元生  盛吉虎 《现代地质》1998,12(1):25-31

南秦岭勉略古缝合带是一个构造混杂岩型非史密斯地层区,由不同时代的原地地层系统和异地地层系统的构造岩片构成。泥盆纪—石炭纪硅质岩的常量元素、稀土元素分析结果指示了勉略小洋盆的存在。区域背景分析表明晚震旦世到早寒武世,南秦岭为扬子板块北部边缘的一部分,中、晚寒武世以后开始分裂形成南秦岭裂陷槽。该海槽于中、晚志留世萎缩但未关闭,泥盆纪又进一步开裂逐渐形成大陆边缘裂谷盆地,晚泥盆世后期到早石炭世早期形成一开放小洋盆。早石炭世后期出现洋壳俯冲,从而转化为活动大陆边缘盆地。该洋盆可能持续到二叠纪,并于印支期最终关闭、碰撞和造山。  相似文献   

Chalcopyrite Intergrowths in sphalerite in the Meixian Lead—Zine Deposit,Fujian Province and their Metallogenic Significance   总被引：2，自引：0，他引：2  

顾连兴  周兵等 《中国地球化学学报》1998,17(4):311-319

Ore textures and electron microprobe analyses show that in addition to highly scattered blebs in sphalerite grains,intergrown chalcopyrite also occurs as rods,myrmekites and lamellae aligned along cleavages and twin boundaries of the host sphalerite.The majority of the intergrowths could have been formed by replacement of sphalerite by chalcopyrite,albeit part of them may have resulted from exsolution,Not only copper,but also iron were introduced into the sphalerite by replacive fluids.While the front of the replacing fluid was moving forward through a sulphide orebody,Zn and Pb were dissolved and Cu was precipitated,resulting in zonal refining of the sulphide ores,The remobilized zinc and lead were precipitated at favourable sites with changed physico-chemical conditions .This is a possible mechanism for the formation of copper-poor zinc and lead ores above or lateral to the copper orebodies in some of the massive sulphide deposits reworked and overprinted by late-stage granites and their hydrothermal fluids.  相似文献   

女姑山跨海桥基施工用钢平台设计   总被引：1，自引：0，他引：1       下载免费PDF全文

顾元威  于吉太 《探矿工程》1998,(1):33-35

结合青岛女姑山跨海桥基工程实践,介绍海滨钢平台设计的基本程序与方法。  相似文献   

An Interpretation of the Non-Tidal Secular Variation in the Earth Rotation: the Interaction Between the Solar Wind and the Earth's Magnetosphere     

Zhennian Gu 《Astrophysics and Space Science》1998,259(4):427-432

The long period variation of the earth rotation is generally explained by the tidal friction. The tidal friction, however, is not the only source to influence the earth rotation in long term. In this paper, by means of the interaction between the solar wind and the magnetosphere of the earth, the additional magnetic pressure will exist in the magnetic tail due to the crowding and sparseness of the magnetic lines in the consideration of the earth rotation, which could be considered as a source of effecting the long term variation of the earth rotation. It is shown in this paper that this mechanism can produce angular deceleration of the Earth rotation in the magnitude of ω = −1.7 × 10-22 s-2. This result might be a prompt to search for other sources in the secular variation of the rate of the Earth rotation variation further in order to regulate the observed result with the theoretical one. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Multi-object fiber-fed spectroscopy     

P. Felenbok  J. Guérin  R. Bellenger  M. Dreux  A. Fernandez 《Astrophysics and Space Science》1990,171(1-2):297-300

We are presenting a multi-object instrument for spectrography in a large field. It is of the arm design as MX or ARGUS. The MEFOS (Meudon-ESO Fiber Optical System) version is built to be used at the ESO 3.60 m prime focus with the triplet corrector. The FIFI (Franco-Italian Fiber Instrument) version, a copy of MEFOS, is shared between the Bologna Observatory and the Paris-Meudon Observatory and will be used, on a visitor basis, at the CFHT prime focus. The instrument carries 30 independent arms with an imaging capability on each arm. It is a modular design with its electronic implemented on each arm. The system is under control of anti-collision software and the whole instrument is driven by an PC/XT-type computer.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.  相似文献   

On the relationship between tropical cyclone size and environmental helicity in the South China Sea          下载免费PDF全文

Min Li  Kekuan Chu  Jian-Feng Gu  Zhe-Min Tan 《大气和海洋科学快报》2022,15(4):100205

In this study, the impact of environmental factors on tropical cyclone (TC) outer-core size was investigated for both migrating and local TCs in the South China Sea during the period 2001–2019. Among all the thermodynamic and dynamic factors, the low-level environmental helicity showed the strongest positive correlation with TC outer-core size. Large helicity favors the development and organization of convection in TCs, and the corresponding strong inflow and large angular momentum fluxes into the system is beneficial for the maintenance and enlargement of TC outer-core size. Besides, the asymmetric distribution of helicity may account for the asymmetry of TC outer-core size. Therefore, the environmental helicity, as an integrated dynamic factor, can provide an alternative view on TC outer-core size.摘要本文利用2001–2019年间的ERA5再分析数据集和热带气旋 (TC) 最佳路径观测, 分析了中国南海TC的外围尺度与环境变量之间的关系. 研究发现, 低层环境螺旋度与TC外围尺度具有显著的正相关. 大的环境螺旋度有利于TC外围对流的增强和组织化, 与之对应的径向入流和角动量输送有利于TC外围尺度的维持或扩张. 此外, 螺旋度的非对称分布与TC外围尺度的非对称性结构也密切相关. 环境螺旋度作为一个包含TC外围对流强度和组织化程度等信息的综合动力因子, 为理解TC外围尺度变化提供了不同的视角.  相似文献   

高速公路团雾分级预警研究     

卢振礼  杨成芳  郑宗杰  等. 《气象与环境科学》2022,45(1):103-111

团雾和高速公路团雾的定义内涵外延尚未统一,没有标准定义。为有效预防高速公路团雾天气灾害,减少因高速公路团雾所造成的交通事故,有必要规范高速公路团雾分级预警标准。基于高速公路团雾的水平能见度和水平尺度等监测数据,借鉴部分学者专家的意见和建议,确定团雾和高速公路团雾的定义。分析高速公路团雾的特征、成因、时空分布及团雾的危害,统计分析高速公路团雾多发路段的交通事故数据资料与AWMS气象监测数据资料,确立高速公路团雾与车辆交通安全性关系。依据同车道前后车辆的相对停车视距和安全停车距离等分析,评估车辆在不同水平能见度数值条件下,行驶在团雾区域内外车辆发生交通事故的危险性大小,遵照相关法律、条例、标准及其规范,按水平能见度数值范围和覆盖路面长度划分高速公路团雾预警等级。研究结果表明:(1)高速公路团雾的水平尺度一般小于5 km,水平能见度通常小于200 m。(2)高速公路团雾具有多发性,时空分布不均,多发生于当日22时次日08时。(3)高速公路团雾的事故率高,造成的交通事故比较严重。(4)可以根据团雾特征和潜在危害性确定团雾和高速公路团雾定义的内涵外延,给出术语定义。(5)可根据高速公路团雾的水平能见度、交通事故、停车视距等分析,划分预警级别,规范监测和预报预警服务,减少交通事故的发生。  相似文献