A reconnaissance study of oxygen, hydrogen and strontium isotopes in geochemically diverse lakes, Western Nebraska, USA   总被引：1，自引：1，他引：0  

David C. Gosselin  Peter E. Nabelek  Zell E. Peterman  Steve Sibray 《Journal of Paleolimnology》1997,17(1):51-65

Reconnaissance ¹⁸O,, D, and ⁸⁷Sr data for fifteen lakes in the Western Lakes Region of the Sand Hills of Nebraska indicate dynamic hydrologic systems. The rather narrow range of ⁸⁷Sr from lake water (1.1 to 2.1) and groundwater (0.9 to 1.7) indicates that the groundwater is generally unradiogenic. Groundwater residence times and relatively unradiogenic volcanic ash within the dune sediments control the ⁸⁷Sr values. Based on the mutual variations of ¹⁸O and D, the lakes can be divided into three groups. In Group 1, both ¹⁸O and D values increase from spring to fall. The ¹⁸O and D values in Group 2 decreased from spring to fall. Group 3 are ephemeral lakes that went dry some time during 1992. The data and isotopic modeling show that variations in the ratio of evaporation relative to groundwater inflow, local humidity conditions, and the _a has substantial influence on the isotopic composition. In addition, isotopic behavior in ephemeral lakes can be rather unusual because of the changing activities of water and mineral precipitation and redissolution. The annual and interannual isotopic variability of these lakes which is reflected in the paleonvironmental indicators may be the rule rather than the exception in these types of systems.  相似文献   

东天山康古尔金矿床成矿流体地球化学特征及其来源   总被引：15，自引：1，他引：14  

张连昌  姬金生 《地球化学》1999,28(1):18-25

新疆康古尔金矿床是分布于晚古生代火山岩区受脆韧性剪切带控制的蚀变岩型金矿。该矿床成矿流体具有中低温度（３２０～１００℃）、中等ＮａＣｌ质量分数（１１４％～１７０％）、弱还原等特征。包裹体气相成分以Ｈ２Ｏ和ＣＯ２为主,液相成分中富Ｎａ＋、Ｃｌ－,而贫Ｋ＋、Ｆ－。成矿流体δＤ为－４５‰～－６６‰,δ１８Ｏ为－８３４‰～２９８‰,（８７Ｓｒ／８６Ｓｒ）ｉ值为０７０７７～０７１０６,反映了成矿流体由变质水、大气降水和岩浆水混合组成的特点  相似文献   

河南西峡晚白垩世恐龙蛋化石壳超高异常Sr的发现及其意义   总被引：5，自引：0，他引：5  

朱光有  钟建华  周瑶琪  陈清华  姜在兴  谢宏亮 《沉积学报》1999,17(4):659-662

利用电感耦合等离子体发射光谱仪(ICP-AES),对采自河南西峡晚白垩世的十三枚恐龙蛋化石壳及蛋内充填物和部分围岩进行了测试。发现Sr元素具有明显的超高异常。恐龙蛋化石壳中的Sr的含量分布在1962×10-6～11010×10-6之间,平均5532×10-6,比古代和现代富Sr的腕足类外壳高一到数倍,比地壳丰度值高一个数量级还多。这种超高异常可能与恐龙蛋壳中含有一定数量的文石有关。而由于文石稳定性较差,在石化过程中会逐渐向低镁方解石转化,所以现在已无法再见到蛋壳中的文石,但Sr却保留了下来。反映了中生代时陆生爬行动物的蛋壳与海相生物硬壳一样具有文石和方解石共存的局面。  相似文献   

青藏高原的隆起与海洋锶同位素组成的演化   总被引：5，自引：2，他引：3  

李春雷  陈骏 《地球科学进展》1999,14(6):582-588

近年来,随着构造隆升驱动气候变化假说的提出,青藏高原的隆起受到越来越多的关注,并将之与大陆化学风化速率及海洋锶同位素的演化紧密联系。围绕青藏高原的隆升及其环境与气候效应,对海洋锶同位素组成的演化特征及其影响因素的较为全面而详细的论述表明:将青藏高原的隆升与全球气候变化、大陆化学风化速率及海洋锶同位素组成的演化相联系,也许是解决目前关于海洋锶同位素组成的演化及其物源问题的重要手段,根据海洋锶同位素的演化历史来研究全球气候变化规律及青藏高原的构造演化历史将是本研究领域的重点。  相似文献   

中国(天青石)锶矿床概述   总被引：8，自引：0，他引：8  

薛天星 《化工矿产地质》1999,21(3):141-148

中国 (天青石 )锶矿资源丰富 ,矿床以大型、特大型单一 (天青石 )锶矿为主 ,构成我国目前主要的工业锶源。依据成矿作用和成矿地质特征 ,将我国 (天青石 )锶矿床划分为沉积型、岩浆 热液型、沉积 热卤水改造型和表生淋积型等四大类七个亚类。主要产于印支、燕山、喜马拉雅三个旋回之中 ,不同类型矿床分别与一定的大地构造环境、沉积岩相、岩浆岩、热液及热卤水等作用有关。中国四川东南部、柴达木盆地东北部、苏南、鄂东南、云南云龙 -维西一带、陕西黄龙铺及四川攀西等 7个地区具有良好的找矿前景  相似文献   

Strontium and neodymium isotopic compositions of detrital sediment of NS90-103 from South China Sea: Variations and their paleoclimate implication     

WEI Gangjian  GUI Xuntang  LI Xianhua  CHEN Yuwei  YU Jinsheng 《中国科学D辑(英文版)》2000,43(6):596-604

Strontium, neodymium isotopic compositions and trace elements of the detrital sediments of Core NS90-103 from South China Sea were analyzed. The results show that the⁸⁷Sr/⁸⁶Sr ratios of the detritus during the last glacial range from 0.722 4 to 0.723 0. They are significantly higher than those during the Holocene and the maximum of the last interglacial, which range from 0.721 0 to 0.721 7. This indicates stronger continental weathering during the last glacial. On the other hand, the¹⁴³Nd/¹⁴⁴Nd ratios of these detritus are higher during the last glacial too, similar to the variation of the⁸⁷Sr/⁸⁶Sr ratios. The trace element geochemistry of these detritus indicates that more authigenic sediments, such as ferromanganese, during the last glacial may partly contribute to the increase of¹⁴³Nd/¹⁴⁴Nd ratios. Furthermore, much more detritus from continent of South China to the north of the South China Sea may probably contribute to¹⁴³Nd/¹⁴⁴Nd ratios increase during the last glacial, which was the result of the enhancement of northeast monsoon.  相似文献   

Variations of U and Sr isotope ratios in Alsace and Luxembourg rain waters: origin and hydrogeochemical implications     

Franois Chabaux  Jean Riotte  Anne-Dsire Schmitt  Jean Carignan  Pierre Herckes  Marie-Claire Pierret  Henry Wortham 《Comptes Rendus Geoscience》2005,337(16):4612

Major and trace element concentrations, as well as Sr and U isotope ratios, were measured in rainwater samples collected in three different locations in Alsace (East of France) and Luxembourg: a mid-altitude mountain site (Aubure Environment HydroGeochemical Observatory), an urban site (Strasbourg) and a peri-urban site located in an area of well developed industrial activity (Esch-sur-Alzette in Luxembourg). Results highlight the quite high spatial and temporal variability of the chemical and isotopic characteristics of rainwater at the regional scale. They also suggest a quite systematic contribution of a local component in the chemical composition of rainwater. In urban and peri-urban sites, the local component is certainly linked to human activities, as it is well illustrated in this study with the Esch-sur-Alzette samples. On the other hand, for the Aubure site, i.e. a small forested watershed of mid-altitude mountain, data presented in this study demonstrate the influence of the vegetation on the chemical composition of rainwater for alkali and calc-alkali elements, as well as for the Sr isotope ratios. Such a result questions the reliability of the method classically used to estimate the rainwater contribution on the river chemical budget. In addition, data of the present study confirm the very low content of uranium in rainwater and demonstrate, especially through the U isotope analysis of Aubure rainwater, the negligible effect of rainwater on U budget of river waters. This work thus outlines the property of U to be a geochemical tracer specific of weathering fluxes carried by rivers. To cite this article: F. Chabaux et al., C. R. Geoscience 337 (2005).  相似文献   

滇黔北坳陷寒武系碳酸盐岩古海洋环境特征及地质意义   总被引：1，自引：1，他引：0  

王鹏万  斯春松  张润合  李娴静  马立桥  黄羚  徐云俊  鲁慧丽 《沉积学报》2016,34(5):811-818

为厘定滇黔北坳陷寒武系碳酸盐岩古海洋环境,揭示成岩流体与岩溶作用的潜在联系,并预测有利储层发育层段,基于镇雄羊场碳酸盐岩剖面实测及系统取样基础上,采用微量元素、碳氧锶同位素及铸体薄片等分析手段,地球化学与岩石学方法相结合,探讨碳酸盐岩古海洋环境及地质意义。研究结果表明:滇黔北坳陷寒武系清虚洞组-娄山关组整体为海相环境,古海洋温度处于12.82℃~32.84℃之间,主体为温暖或炎热的亚热带气候。海平面具有主体震荡下降的趋势,存在8期海平面变化旋回,发育对应的岩相组合,其同位素演化曲线可作为地层划分依据。微量元素、同位素地球化学及岩石学特征证实娄山关组岩溶作用相对发育,成岩流体混入强氧化性低温大气水,有利储层纵向上主要分布在海平面下降旋回的高部位。  相似文献   

四川盆地东部垫江盐盆早三叠世嘉陵江组四段杂卤石成因及对成钾的指示          下载免费PDF全文

张雄  朱正杰  崔志伟  赵艳军  贺赤诚  胡峰  王开文 《地球科学》2022,47(1):27-35

四川盆地三叠纪是主要的成钾期,目前发现的主要含钾矿物为杂卤石,有关早三叠世嘉陵江组四段石盐岩中杂卤石成因一直存在争议.采用薄片鉴定、扫描电镜、稀土元素和锶同位素等手段,分析了四川盆地东部垫江盐盆长寿地区嘉陵江组四段石盐岩中杂卤石矿物形态特征,初步探讨了该杂卤石成因及对寻找海相钾盐的指示意义.扫描电镜下与石盐岩共生的杂卤...  相似文献   

陕北贾大峁遗址出土动物遗骸的锶同位素比值分析     

赵春燕  胡松梅  杨苗苗  郭小宁  杨瞳 《第四纪研究》2022,42(1):59-68

史前时期动物驯养技术的跨大陆交流与传播是令人瞩目的 前沿课题.陕北地区位于欧亚草原早期青铜文化和中原地区古代文化交汇碰撞的前沿地带.贾大峁遗址位于陕西省横山县,年代为距今约4500～4300年的龙山早期.作为陕北地区目前发现的最早出现牛和羊的考古遗址之一,牛和羊是当地驯养抑或外来的,是值得我们探讨的问题.本文通过热电离...  相似文献