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1.
华南诸广山复式岩体中段花岗岩的碱交代蚀变 总被引：8，自引：0，他引：8
诸广山复式花岗岩体中段某大型铀矿田中的部分花岗岩广泛发育碱交代蚀变作用。据对３１３个碱交代蚀变花岗岩样品的岩石化学分析资料及岩相学研究结果表明,该地碱交代蚀变是以钠长石化为主的多阶段钾、钠叠加交代（即混合交代）,蚀变强度大多较弱,局部可较强并生成二长石岩、钠长石岩等交代蚀变岩。测得该碱交代蚀变岩石的Ｒｂ－Ｓｒ等时线年龄为１３２．１±５．８Ｍａ,在时序上它与主体侵入的似斑状黑云母花岗岩（Ｒｂ－Ｓｒ等时线成岩年龄为２１５．２±６．３Ｍａ）、补体侵入的细粒少斑黑云母花岗岩（测得Ｒｂ－Ｓｒ等时线成岩年龄为１５５．２±５．４５Ｍａ）构成一连续演化序列,推测碱质可能源自该产铀花岗岩岩浆演化钠转折分异阶段的产物;该蚀变岩属铀成矿前已遭剥蚀的钨、锡矿化矿根相,成为随后工业铀矿化（Ｕ－Ｐｂ法测得成矿年龄为１０３．２±０．６Ｍａ）的有利围岩。 相似文献
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3.
四平银（金）矿床石英包裹体 Rb－Sr等时线年龄 187± 4 Ma，表明首期成矿作用发生在燕山早期，矿床 Rb－Sr等时线年龄与蚀变绢云母 K－Ar年龄差异及不同矿段矿化特征差异表明，蚀变绢云母 K－Ar年龄反映后期热液成矿事件时代，四平银（金）矿床至少经历了两期热液成矿事件，首期成矿事件发生在燕山早期，晚期成矿事件发生在燕山中期，成矿热液活动时间跨度约 33 Ma。 相似文献
4.
新疆北部索尔库都克铜（钼）矿床年代学研究 总被引：6，自引：0，他引：6
对新疆阿尔泰地区索尔库都克似矽卡岩型岩浆热液铜矿床进行了年代学研究，分别获得赋矿围岩Ｒｂ－Ｓｒ等时线年龄为２８８±１７Ｍａ，含矿似矽夺中的石榴石及绿帘石矿物Ｓｍ－Ｎｄ等时线年龄为２８４±４Ｍａ，测定结果表明，蚀变安山岩年龄比所处地层时代明显地偏年轻，表明其受到了后期改造，其改造年龄和该矿床的成矿时代一致，都为早二叠世，与新疆北部晚石炭世末－早二叠世的区域性造山后拉张－岩浆热事件有关。 相似文献
5.
本文给出的滹沱群下亚群青石村组玄武岩Ｒｂ－Ｓｒ、Ｓｍ－Ｎｄ全岩等时线年龄为２０４５．８±１７和２３６９±３０Ｍａ（Ｚ），角门石４０Ａｒ－３９Ａｒ坪年龄和最高视年龄为１３６４±１９和１９３２±１９Ｍａ（１）；中亚群河边村组玄武岩Ｒｂ－Ｓｒ全岩等时线年龄图的投点呈完全离散状，Ｓｍ－Ｎｄ全岩等时线年龄为２３２２±３１Ｍａ（２），角门石４０Ａｒ－３９Ａｒ坪年龄和最高视年龄为１３６０和１７４２±１７Ｍａ（１）。根据上述Ｒｂ－Ｓｒ、Ｓｍ－Ｎｄ数据与已知青石村组、河边村组单颗粒锆石Ｕ－Ｐｂ法确定的成岩年龄２４５０±１０和２４００±２０Ｍａ（２）的明显差别，４０Ａｒ－３９Ａｒ均揭示为较典型受扰动的年龄谱和较发育的透人性构造、晚期岩脉等地质证据，认为Ｒｂ－Ｓｒ、Ｓｍ－Ｎｄ是重设的同位素体系。 相似文献
6.
早元古代滹沱群玄武岩Rb—Sr,Sm—Nd同位素体系初论 总被引：6，自引：0，他引：6
王汝铮 《前寒武纪研究进展》1997,20(1):35-43
本文给出了的滹沱群下亚群青石村组玄武岩Ｒｂ－Ｓｒ、Ｓｍ－Ｎｄ全岩等时线年龄为２０４５．８±１７和２３６９±３０Ｍａ（２σ），角闪石＾４０Ａｒ＾－＾３９Ａｒ坪年龄和最高视年龄为１３６４±１９和１９３２±１９Ｍａ（１σ）；中亚群河边村组玄武岩Ｒｂ－Ｓｒ全岩等时线年龄图的投点呈完全离散状。 相似文献
7.
小秦岭303号石英脉流体包裹体Rb—Sr,^40Ar—^39Ar成矿年龄测定 总被引：10，自引：2，他引：8
用石英流体包裹体Ｒｂ－Ｓｒ、＾４０Ａｒ－＾３９Ａｒ法测定了小秦岭３０３号石英脉的形成时代为石元古代。其流体包裹体属Ｈ２Ｏ＋ＣＯ２＋ＣａＣｌ型,盐度为６．５％－１２．９８％,ＣＯ２含量高,Ｎａ＾＋〉Ｋ＋。３０３号石英脉Ｒｂ－Ｓｒ等时线年龄为（２３８２±３３６）Ｍａ－（２２３４±４７）Ｍａ,（＾８７ｓＲ／＾８６Ｓｒ）ｉ为（０．７３５１±０．００１９）－（０．７４１６±０．０００４）,＾４０Ａｒ＾＾３９ 相似文献
8.
浙江毫石银矿床成矿年代学和同位素地球化学 总被引：5，自引：0，他引：5
文章通过矿脉中蚀变绢云母的Ｋ－Ａｒ年龄和石英流体包裹体的Ｒｂ－Ｓｒ等时年龄测定，得出毫石银矿床的成矿年龄为１００×１０＾６ａ。该成矿年龄相对于本区上侏罗统火山岩的成岩年龄要滞后≥３０×１０＾ａ。同时，对该银矿床进行了较系统的Ｈ、Ｏ、Ｓ及Ｐｂ等同位素地球化学研究，判别其成矿热液来自中生代大气降水成因的环流地热水，通过淋滤作用汲取岩石中的成矿物质，形成了浅成中低温热液充填型银矿床。 相似文献
9.
安徽沙溪斑岩铜（金）矿床成岩成矿热历史探讨 总被引：12，自引：1，他引：11
采用Ｒｂ－Ｓｒ方法,测定沙溪斑岩铜（金）矿成矿岩体年龄为１４３．３７±５．１７Ｍａ;采用＾４０Ａｒ／＾３９Ａｒ快中子活化定年法,测定沙溪斑岩铜（金）矿成矿年龄为１２３．６±０．７Ｍａ;成矿岩体从固结成岩到成矿经历了２０Ｍａ。根据Ｒｂ－Ｓｒ和Ｋ－Ａｒ同位素体系封闭温度的不同,估算出沙溪岩浆热液成矿系统热衰减速率平均为２０℃／Ｍａ。单一的由成矿小岩体所提供的热能难以维持如此长时间热液成矿活动,矿区晚期 相似文献
10.
内蒙古毛登锡铜矿床地质及成因 总被引：2，自引：3，他引：2
内蒙古毛登锡铜矿床是大兴安岭南段的锡多金属矿床之一。该矿床是与阿鲁包格山花岗斑岩（Ｒｂ－Ｓｒ等时线年龄１４９×１０＾－６ａ），锶同位素初始比值为０．７０５）有关的具中等成矿深度和成矿温度的热液脉型锡铜矿床。矿床中主要产出锡矿体，它们分别以微脉、细脉和大脉的形式充填于自接触带向外的ＮＷ向断裂裂隙系统中。钾化（磁铁矿矿化）、云英岩化（锡石或辉钼矿矿化）和硅化（硫化物矿物）三个蚀变－矿化阶段流体的温度和 相似文献
11.
中国东部新生代玄武岩中巨晶矿物的地球化学 总被引：13，自引：0，他引：13
本文对安徽女山、河北汉诺坝和广东普宁碱性玄武岩中的单斜辉石和角闪石巨晶进行了主要元素、稀土元素、微量元天和Ｓｒ＿Ｎｄ同位素的综合分析。数据显示产出于３个研究区的单斜辉石巨晶有３类：Ａｌ普通辉石、透辉石和Ｆｅ＿Ｎａ透辉石。普宁地区的角闪石巨晶乃世界上罕见的绿钙闪石巨晶。女山和普宁的单斜辉石和角闪石巨晶是碱性玄武岩浆在幔源高压下的结晶产物；汉诺坝的单斜辉石巨晶既可以是碱性玄武岩浆又可以是拉斑玄武岩浆的高压结晶体。所有巨晶相对于寄主岩者属于偶然捕掳晶。巨晶的形成符合“流动结晶模式”。它们与共存的橄榄岩色体无成因 相似文献
12.
Green clinopyroxenes and associated phases in a potassium-rich lava from the Leucite Hills,Wyoming 总被引：1，自引：0，他引：1
Green, salitic pyroxenes occur as megacrysts and as cores in diopsidic pyroxene phenocrysts and microphenocrysts in a wyomingite lava from Hatcher Mesa, Leucite Hills, Wyoming. Al-rich phlogopite (16–21% Al2O3), apatite, Fe-Ti-oxide, Mg-rich olivine (Fo93) and orthopyroxene (En61) also occur as megacrysts or as inclusions in diopside phenocrysts. All of these phases are found in ultramafic xenoliths in the host lava, and petrographic and chemical evidence is presented that the megacrysts originate by the disaggregation of the xenoliths. It is concluded that the latter are accidental fragments of the wall rocks traversed by the wyomingite magma and it is suggested that the clinopyroxene-rich xenoliths, from which the green pyroxenes are derived, formed in the upper mantle as a result of local metasomatism or by crystallization from magmas of unknown composition during an earlier igneous event. The precise role of the clinopyroxene-rich xenoliths (which also contain apatite, Fe-Ti-oxide and amphibole) in the genesis of the Leucite Hills magmas cannot be elucidated on the basis of the available data, but it is unlikely that they represent the source material from which these magmas are derived. 相似文献
13.
Discovery of Pyrrhotite-Chalcopyrite-Bearing Amphibole Megacrysts in Tongling Area, Anhui Province 总被引：1，自引：0，他引：1
Some pyrrhotite-chalcopyrite-bearing amphibole megacrysts (including pyroxene megacrysts) were discovered in Mesozoic augite diorite-porphyrite at Caoshan in Tongling area, Anhui Province. The amphibole megacrysts, belonging mainly to pargasite and magnesiohastingsite, are characteristic of the amphibole composition derived from mantle and crystallized in lower crust. In general, the aggregates of pyrrhotite-chalcopyrite take the shapes of cylinder and sphere. Three occurrences have been recognized in the amphibole megacrysts: parallel linear, bunchy and scattered. The unique cylinder-like shape of the aggregates and remarkable Ni-poor sulfides in Caoshan are distinctively different from the spherical Ni-rich sulfides in pyroxene megacrysts and any other kinds of megacrysts. In terms of composition, the amphibole megacrysts and their sulfides in Caoshan are similar to those in the pyroxenite xenoliths in Qilin, Guangdong Province. In terms of origin, the pyrrhotite-chalcopyrites as exsolution products resulted from the subsolidus re-equilibration of sulfide solid solution within amphibole megacrysts.amphibole megacrysts were first discovered inside and outside China. This discovery is important for the study of regional magma evolution and its associated mineralizations and ore sources as well. 相似文献
14.
安徽女山单斜辉石巨晶的地球化学 总被引：14，自引：0，他引：14
本文研究了安徽女山14个单斜辉石巨晶。它们属于铝普通辉石、透辉石和铁钠造辉石。主要元素、稀土和微量元素及同位素特征表明：它们是同一碱性玄武岩浆在幔源条件下不同程度结晶分异的产物，相对于寄主岩均属捕虏晶，可能自中生代即已开始形成。 相似文献
15.
The tuff and basanite of Rosenberg 20 km NW of Kassel are thus far unknown occurrences of megacrysts and polycrystalline aggregates of pargasitic-kaersutitic amphibole and of xenoliths of amphibole-bearing peridotite and pyroxenite. The amphiboles precipitated successively with gradually increasing Fe/Mg from the same magma from which the basanite was ultimately derived. The amphibole fractionation commenced within the upper mantle but may have continued into higher levels within the ascending melt.Amphibole and phlogopite fractionation together caused an increased Na/K ratio in the Rosenberg basanite. The crystallization of amphibole and phlogopite is genetically interrelated with the violent eruptive nature of the Rosenberg volcano. The release of vapour during the final stage of amphibole crystallization is indicated by the existence of coarsely vesicular amphibole megacrysts. 相似文献
16.
延边地区中生代火山岩的岩浆源区:来自Sr-Nd同位素和深源捕虏体(晶)的证据 总被引：6，自引：0，他引：6
延边地区中侏罗世和早白垩世火山岩中包含有较多的辉石岩捕虏体和角闪石捕虏晶,前者为普通辉石变种,其化学成分类似于中国东部新生代玄武岩中单斜辉石巨晶的成分,具有岩浆堆积成因特征;后者为韭闪石和镁质绿钠闪石变种,其成分类似于中生代晚期玄武岩中角闪二辉石岩包体里的角闪石和新生代玄武岩中的角闪石巨晶.矿物温压计算结果显示,它们形成深度介于25～37km.延边地区中生代火山岩的(87Sr/86Sr)i值介于0.704 3～0.705 0,εNd(t)值介于2.33～4.71,表明岩浆源区应是一套具有亏损性质的新增生的地幔物质.综合上述结果,可以判定延边地区中生代火山岩的原始岩浆应来源于新增生的壳幔过渡带物质的部分熔融,地壳增生事件的时间为新元古代. 相似文献
17.
华北晚中生代和新生代玄武岩中单斜辉石巨晶来源及其对寄主岩岩浆过程的制约:以莒南和鹤壁为例 总被引：3，自引：0，他引：3
本文对华北克拉通晚中生代和新生代碱性玄武质岩石中的单斜辉石巨晶进行了主、微量元素和Sr-Nd同位素的综合研究,发现晚中生代和新生代单斜辉石巨晶存在明显的主、微量元素和同位素组成上的差异。新生代单斜辉石巨晶有Al-普通辉石和次透辉石两类;而中生代单斜辉石巨晶只有Al-普通辉石。新生代单斜辉石SiO_2含量高、REE配分型式为上凸型、LILE和放射性元素含量高,并具有比寄主碱性玄武岩更亏损的Sr和Nd同位素组成;而中生代单斜辉石SiO_2含量低、REE配分型式为LREE富集型、LILE和部分HFSE以及放射性元素含量低,并具有比寄主碱性玄武岩稍富集的Sr和Nd同位素组成;巨晶的结构、矿物成分和地球化学特征,以及Mg-Fe在熔体与单斜辉石间的分配状况皆说明,新生代碱性玄武岩中单斜辉石巨晶是碱性玄武岩浆在高压下结晶的,因此二者是同源的;而中生代单斜辉石巨晶是被寄主岩浆偶然捕获的捕虏晶,是不同源的。华北新生代单斜辉石巨晶存在于碱性玄武岩和拉斑玄武岩中,它们具有比寄主碱性玄武岩更亏损的Sr和Nd同位素组成,说明即使是碱性玄武岩也不能完全代表软流圈来源的原始岩浆,其在上升过程中或多或少存在同位素组成富集的物质的混入。同时,拉斑玄武岩不是碱性玄武质岩浆直接结晶分异的产物,亦不是完全由部分熔融程度的不同造成的。拉斑玄武岩中存在岩石圈地幔物质的贡献或是岩浆房内碱性玄武质岩浆受地壳混染作用的结果。 相似文献
18.
岩体地质简述马关县南部已发现的4个玄武岩火山颈和12条煌斑岩岩脉都分布在木厂一老厂一带。区内主要发育泥盆纪地层,大地构造位置在华南台块滇桂台向斜的西南角。褶皱平缓,主要是一些成北东走向长度不过几公里的短轴背斜和短轴向斜。沿褶皱走向常有一些断裂,顺着这些断裂有许多辉长辉绿岩小侵入体。蒿子坝火山颈位于老厂篙子坝村北约二百米处,是群峦丛中一个低低的小峰,呈椭圆锥状,高出地面不过二、三十米,其根部水平截面长径为近东西方向,长85米,短径60米(图1)。火山颈由两个岩相组成:中央相是由玄武岩胶结的火山角砾岩;边缘相是含橄榄岩捕虏体的玄武岩,岩相宽度不过几米。煌斑岩岩脉多牛夹在沉积岩岩层间,其产状好象岩床。猫耳岩"岩床"位于木厂节节坡村南一里许,岩体出露在猫耳岩峭壁的根部,厚2-3米,长128米(图2)。 相似文献
19.
Strontium isotopic data for megacrysts and lavas from six eruptive centers within the Newer Basalts province of southeastern Australia show that megacrysts of clinopyroxene are in isotopic equilibrium with associated basalts, but that megacrysts of kaersutite, ferrokaersutite, orthopyroxene and anorthoclase may exhibit slight disequilibrium with their host basalts. Furthermore, the anorthoclase megacrysts may be either more or less radiogenic than their hosts. The 87Sr/86Sr ratios for 14 basalts from throughout the province vary from 0.7035 to 0.7045 and it is proposed that anorthoclase, amphibole and orthopyroxene megacrysts which crystallized in isotopic equilibrium with one magma may have been caught up in a pulse of a later magma of a different isotopic composition. The variations in the 87Sr/86Sr ratios for the basalts are attributed to variations in the isotopic composition of their source regions. Such isotopic heterogeneity is supported by published data for ultramafic xenoliths which occur in the Newer Basalts lavas. 相似文献
20.
Ten lherzolite xenoliths collected on Nunivak Island, Alaska,contain interstitial chromian pargasitic amphibole. Of 2000lherzolite nodules examined from the maars of the island, however,50 per cent contain relics of such an amphibole in the formof fine-grained zones of euhedral diopside, olivine and spinelin a porous Al-rich glass. These nodules are believed to havebeen amphibole-bearing fragments of the upper mantle, that partiallymelted during their ascent to the surface in the Nunivak basalts.The textural intimacy and chemical zoning exhibited by the interstitialamphibole and spinel in the lherzolite xenoliths indicate thatalthough the amphibole predates the Nunivak basalts, it is asecondary aluminous phase. The amphibole was formed in the uppermantle during a pervasive metasomatic event caused by risingtemperature and the infiltration of alkali-rich fluid, priorto the introduction of basaltic magmas. 相似文献