中国某些花岗岩的Sr-O同位素体系

花岗岩类岩石δ~(18)O和~(87)Sr/~(86)Sr初始比值的关系可分为四种类型:封闭结果型:呈近于垂直的短线;硅铝物质重熔型:呈负相关关系;壳幔混合型:呈正相关关系;水-岩交换型:基本为无相关。     

中国某些花岗岩δD与H_2O的关系

花岗岩类岩石δD与HH_2O(wt％)的关系可分为三种类型:封闭结晶型(大容山型),呈平缓正相关关系;开放去气型(崂山型),呈近于垂直的相关关系;大气降水热液交换型(告乌型),呈不规则略具负相关趋势。     

花岗岩类岩石H-O同位素体系的纬度和高度效应

中国东部沿海和西藏南部广泛分布有中、新生代的花岗岩类岩石。为了研究它们H-O同位素体系的纬度和高度效应,我们首先研究了现代大气降水δD,δ~(18)O值的高度和纬度效应。在此基础上,我们研究了西藏拉萨-亚东地带花岗岩类岩石中羟基矿物的δD值。它们具有明显的高度效应。根据黑云母δD值计算出来的西藏高原在20—40Ma期间的年平均隆起速度为0.1mm。中国东部沿海燕山晚期晶洞花岗岩全岩δ~(18)O,δD值具有明显的纬度效应。每个岩体中δ~(18)O-δD值之间的负相关关系代表在热水-岩石相互作用体系中ω/r比相同条件下温度与岩石δ~(18)_O,δD值的关系。     

华南花岗岩型铀矿床成矿热液中∑CO_2来源研究

本文根据多种制约手段,探讨了华南花岗岩型铀矿床成矿热液中∑CO_2的来源。结果表明,形成产铀岩体的高酸度花岗岩浆分异不出富∑CO_2的流体;华南3个铀主成矿期成矿热液中的∑CO_2均来自地幔,并分别受三期地壳拉张作用的控制。研究结果合理地解释了富铀花岗岩浆分异结束后为什么不能成矿,以及花岗岩型铀矿床为什么集中在富铀花岗岩体形成后的地壳拉张期成矿。     

δ~(18)O CONTOURS AND ANCIENT FOSSIL HYDRO-THERMAL SYSTEM OF MIAROLITIC ALKA-LINE GRANITE,NIANZISHAN,HEILONGJIANG

The H and O isotope compositions of 41 whole rocks and 24 separated minerals of theNianzishan miarolitic alkaline granite and 3 local meteoric water samples have been meas-ured. The results indicate that the meteoric-hydrothermal convective system might have beendeveloped in this stock. The distributions of δ~(18)O values of whole-rock samples formed anapproximateIy δ~(18)O contours with the characteristic of kighest values in the midst and de-creasing toward the outer zones. The water/rock ratio (W/R) contours were also calculated.This phenomenon might have common significance for stocks or plutons.     

Research on ΣCO_2 Source in Ore-forming Hydrothermal Solution of Granite-Type Uranium Deposit, South China

Multi-constraints are used in this paper to discuss the ΣCO_2 source in oreforming hydrothermal solution of granite-type uranium deposit in South China. The studies show that highly acidic and uraniferous granitic magma cannot produce the fluid rich in ΣCO_2. Controlled by three periods of crust extension and corresponding to three major periods of U-mineralization in South China respectively, the ΣCO_2 in each ore-forming hydrothermal solutions is all mantle-derived. Our studies reasonably explain why the mineralization did not occur immediately after the end of differentiation of the granitic magma rich in uranium, and why the ore-forming time of granite-type uranium deposit focuses on the time of crust extension after the formation of the uraniferous granites.     

SR-O ISOTOPE SYSTEM OF SOME GRANITOIDS IN CHINA

Four of Sr- O isotope types can be observed in the graphs of δ~(18)O vs. (~(87)Sr/~(86)Sr)_i accord-ing to our data: (i) closed-system crystallization type: nearly short- vertical line withsimilar initial Sr isotope ratios and small changes of δ~(18)O values(<3‰); (ii) sialic materialremelting type: negative correlations without mantle end member; (iii) crust-mantle contam-ination type: a variety of mixing hyperbolas or straight lines with positive slopes: (iv)water-rock exchange type: irregular distribution.     

“南永1井”礁相碳酸盐C,O,Sr,Pb同位素组成及其古环境意义探讨

“南永1井”礁相碳酸盐的O,C同位素组成可分为四段,它们的δ~(18)O(‰)和δ~(13)C(‰)平均值分别为:(Ⅰ)-5.0,-0.5;(Ⅱ)-7.7,-5.3;(Ⅲ)-6.4,-2.8;(Ⅳ)1.3,2.1.(Ⅱ)段的δ~(18)O值波动曲线以变化频率低、幅度小为特征,与布容期冰期-间冰期存在对应关系;(Ⅲ)和(Ⅳ)段的δ~(18)O和δ~(13)C值之间有正相关,在成因上与白云石化有关。△~(87)Sr和Pb同位素组成同样存在四分的特点。整个钻孔岩芯中△~(87)Sr的最大值和最小值以及全部正值都出现在第Ⅱ段。第Ⅳ段的Pb,sr同位素均呈现变化波动频繁的特点,在白云石化阶段有高μ值的Pb带入。礁相碳酸盐的O,C,Sr和Pb同位素组成记录了南海第四纪古气候、古环境变迁的历史。     

THE ALTITUDE AND LATITUDE EFFECTS OF H-O ISOTOPIC SYSTEM IN GRANITOID ROCKS

A lot of Mesozoic and Cenozoic granitoid rocks are widely distributed along the east coastalregion and in the southern part of Xizang, China. In order to study the altitude and latitude effect ofH-O isotopic system in these granitoid rocks, we have first studied the altitude and latitude effects ofδ~(18)O, δD values of recent meteoric water. The altitude and latitude effect equations of recent meteoricteoric water were established. The altitude effects of δD vaues for hydroxyl minerals from granitoid rocks inLhasa-Yadong region of Xizang were found. The average elevated rate of Xizang Plateau is 0.1 mm/yr.The δ~(18)O and δD values of whole rock samples for late Yanshanian miarolitic granite in the east coastalregion wete progressively lower as a function of latitude. The negative correlation between δ~(18)O and δDvalues in each miarolitic pluton represents the relationship between δ~(18)O, δD values of rocks or mineralsand temperatures in the condition with the same ω/r ratio in the interactiv     

黑龙江碾子山晶洞碱性花岗岩δ~(18)O等值线与古化石热水体系研究

本文分析了碾子山晶洞碱性花岗岩体41个全岩、24个单矿物及当地大气降水的H,O同位素组成,所得结果说明该岩体明显经历过大气降水-岩石相互作用。将全岩样品的δ~(18)O值全部投在地质图上,可画出δ~(18)O内高外低的等值线。计算的水/岩比(W/R)构成形状一致但呈内低外高现象的等值线图,这一现象可能具有普遍意义。