The application of uranium series disequilibrium concepts to sediment yield determination     

A. J. Plater  R. E. Dugdale  M. Ivanovich 《地球表面变化过程与地形》1988,13(2):171-182

The determination of uranium series disequilibria in fluvial environments is proposed as a method of calculating catchment mass balances. The technique is based on two main principles. Firstly, ²³⁴U is more mobile than ²³⁸U, especially during the early stages of weathering. Secondly, uranium is far more mobile than either thorium or protactinium. Consequently, teaching during weathering results in the loss of the uranium found in the fresh rock, leaving the two immobile daughters behind. The ratio of uranium carried by sediment to that dissolved, U_S/U_W can, therefore, be determined from river water and sediment isotopic activity ratios. Fluxes of uranium can then be calculated from average concentrations in the water and the associated sediment, from which a sediment yield can be inferred. The Witham catchment in Lincolnshire has been used to test the proposed method. A U_S/U_W ratio of between 5 and 7 is determined and a sediment yield of 2.51 ± 2.12 tonnes yr^?1 km^?2 is proposed. Although some problems concerning environmental chemistry have arisen, the validity of the approach is confirmed by the close correspondence between the results obtained and those inferred by earlier workers using more conventional methods.  相似文献   

The role of vibrationally excited nitrogen in the ionosphere     

A. V. Pavlov 《Pure and Applied Geophysics》1988,127(2-3):529-544

Theoretical and experimental aspects of the production, transformation, diffusion and loss of N₂ in the upper atmosphere are considered. The N₂-CO₂ near-resonant system in theD andE regions is taken into account. We describe our understanding of the methods necessary to find the vibrational populations of N₂ and CO₂ (asymmetric mode of CO₂). The calculations of the vibrational temperatures in theD, E, andF regions for the mid-latitude ionosphere and an aurora are presented. The connection between the excited species and the 4.26-m radiation intensities is considered. The models for the rate coefficient of the reaction of O⁺ with N₂ and the electron density decrease resulting from N₂ in the F region are discussed.  相似文献   

Isotopic compositional Characteristics of Terrigenous Natural Gases in China   总被引：1，自引：1，他引：1  

沈平  徐永昌 《中国地球化学学报》1993,12(1):14-24

The C and H isotopic compositions of the methane in more than 160 gas samples from 10 basins in China are presented in this paper.The natural gases are classified as four types: biogenic gas ,bio-thermocatalytic transitional gas, gas associated with condensate oil ,and coal-type gas. The isotopic compositions of these gases closely related to the depositional basins, the types of organic matter,the stages of thermal evolution and the genetic characteristics of different gas reservoirs.Studies of the C and H isotopic compositions of terrigenous natural gases will provide valua-ble information on the prospecting and development of natural gases of different genetic types.  相似文献   

同沉积构造及其演化背景分析——以塞文煤盆地为例   总被引：6，自引：0，他引：6       下载免费PDF全文

王华 Courel  L 《地球科学》1993,18(2):129-138

  相似文献   

造盆作用及成矿盆地的历史动力综合分类建议   总被引：3，自引：0，他引：3  

陈国达 《地球科学进展》1993,8(3):30-36

本文把历史分析方法与动力分析方法两种分折方法结合起来,提出了一个综合的盆地分类方案。按历史动力综合分类,造盆作用及盆地可划分为三大类:大洋壳型、雏陆壳(过渡壳)型及大陆壳型大壳型中可细分为活动区型及稳定区型。雏陆壳型包括前地槽型及地槽前期型。大陆壳型中计有地槽后期型、地台型和地洼型。  相似文献   

滇西澜沧变质带中白云母的研究及其地质意义          下载免费PDF全文

赵靖 《岩石矿物学杂志》1993,12(3):251-260

本文以滇西澜沧变质带中最为广泛分布的造岩矿物—白云母为对象，详细研究和 分析了其成分、多型类型及ba值等，探讨了白云母的发育规律。研究结果表明，本带中绝大多数白云母为多硅白云母，且为3T+2M,型，与蓝闪石共生的则以3T多硅白云母为主。此外，斓沧变质 带经历了蓝闪石片岩亚相的高压变质作用，与古特提斯构造演化密切相突，并可与世界著名的高 压带对比。  相似文献   

贵州长顺代化石炭系中间界线的沉积相研究   总被引：3，自引：3，他引：3  

周志澄 《地层学杂志》1994,18(1):1-8,T002

在碳酸盐微相的详细研究基础上，贵州长顺代化下、上石炭统剖面由下至上可分出５个主要沉积相：盆地相、开阔海陆架相、下斜坡相、中斜坡相和上斜坡相，下、上石炭统界线处于连续沉积的中斜坡相内。  相似文献   

Structural Styles of the Longmenshan Thrust Belt and Evolution of the Foreland Basin in Western Sichuan Province, China   总被引：7，自引：0，他引：7  

Liu Hefu  Liang Huishe  Cai Liguo  Shen Fei China University of Geosciences  Beijing Jiang Minxi 《《地质学报》英文版》1994,68(4):351-372

The Longmenshan thrust system consists of two major groups of structural styles according to the depth of their involvement: basement thrusts-compressional fault blocks; fold-thrust system in the cover. In cross-section, the Longmenshan structural belt is divided into 5 zones. The propagation of the Longmenshan thrust system is piggy-back due to pushing at the early stage and overstep due to gravity sliding at the late stage. Balanced cross-sections and palinspastic reconstruction reveal that the total sliding displacement of the thrust system amounts to 120 km. The tectonic evolution of the Tethys domain in western Sichuan has experienced 5 stages: continental break-up; ocean-continent subduction ; continent-arc collision; orogenic thrusting; uplift of western Sichuan.  相似文献   

临汾市东亢锌－锶－偏硅酸优质饮用天然矿泉水     

魏文革 《华北地质矿产杂志》1994,(4)

东亢矿泉水处于临汾断陷盆地边缘山前地带。矿泉水赋存于石炭系、奥陶系及侵入岩体的裂隙中。单井涌水量达７１．４ｍ￣３／ｈ，水位埋深５１．０９ｍ。矿泉水中锌、锶、偏硅酸分别为０．２８９ｍｇ／Ｌ，１．２８ｍｇ／Ｌ，３３．２８ｍｇ／Ｌ，属锌锶偏硅酸－重碳酸·硫酸－钠型优质矿泉水，具有良好的开发前景。  相似文献   

华南变质基底的组成、边界与构造演化（研究综述）   总被引：5，自引：0，他引：5  

汤加富 《安徽地质》1994,(Z1)

本文据作者调查并综合有关资料，就华南变质基底的组成结构、边界性质、构造型式及演化过程作了较全面阐述；就板溪群是否为构造混杂岩，及其所代表的地质体性质作了深入分析和讨论，作者认为：华南可能存在晚太古－早元古统一变质基底，中元古末至印支期为板块活动期，印支期后，由于受太平洋板块作用影响而进入新的构造活动期。  相似文献