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1.
《International Geology Review》2012,54(4):668-681
Microclinization of granites originally enriched in plagioclase forms 1) porphyritic (porphyroblastic) biotite granites; 2) coarse- to medium-grained (even-grained) biotite-, two-mica, and muscovite granites; and 3) pegmatitic granites. Additional post magmatic metasomatic processes effecting granites are early albitization, greisenization, late albitization, and late microclinization. Maximum relative activity of cations in the evolution of post magmatic solutions may be arranged in the following series: K-Na-Si-Al-Na-K or else (with greisenization stage undeveloped) K-Na-K. This series corresponds to the concept of acidity-alkalinity of high temperature post-magmatic solutions and reflects the changes in their acidity at the various stages of metasomatism.--R. M. Hutchinson. 相似文献
2.
The Yinyan porphyry tin deposit is a blind deposit associated with a small granite porphyry stock.The petrology and geochemistry of the Yinyan granite porphyry suggest that it is genetically of the transfor-mation type,emplaced at the late stage of fractional crystallization within a high-level magma chamber.Ore-forming fluids are derived predominantly from the granitic magma and they interact with the wall rocks intensely when finding their way upwards through the granite porphyry.From the lower part of the porphyry upwards the following alteration zones can be distinguished(a)slightly altered granite porphyry (with weak potash feldspathization),(b)protolithionite-quartz greisenization zone,(c)to-paz-quartz greisenization zone,(d)senicite-quartz sericitization zone,and （e）silicification zone (quartz core at the surface).Tin mineralization is related to greisenization,especially to topaz-quartz greisenization.Rock and ore-forming temperatures and oxygen fugacities are estimated,respectively.There are significant differences in many aspects between the Yinyan porphyry tin deposit and volcan-ic-subvolcanic porphyry tin deposits. 相似文献
3.
A.M.R. Neiva 《Chemical Geology》1974,13(4):295-308
Greisenization of a muscovite-biotite albite granite of Alijó-Sanfins, northern Portugal, is studied for both major and trace elements. The principal tin-tungsten mineralization of the region is connected with this granite and the greisenization is accompanied by an increase in Cl, F, W, Nb, Sn, Pb and Rb. Cassiterite is the main carrier of Sn. Muscovite is the concentrator of Cl and F. The muscovite of the greisenized granite contains more Cl, F, W and Nb than the muscovite of the parental granite, but the former contains less Sn. Sn content of the muscovite of the greisenized granite is higher than that of the biotite of the parental granite; W content is similar or higher.When the greisenization is accompanied by albitization, the oxides and trace elements behave in a similar way to that found only with greisenization, except that there is a decrease of Ni and Rb. Li, Zr, Sr, Ba and Rb decrease as albitization increases. 相似文献
4.
The G. Abu Garadi area is covered mainly by metasediments, alkali feldspar granites and stream sediments. The alkali feldspar granite is traversed by a major strike-slip fault trending in an N-S direction as well as two subordinate sets of faults trending NW to WNW for the first one and NE for the second one. These faults represent the shear zones affected by magmatic (syngenetic) as well as hydrothermal (epigenetic) activities causing alteration of the granitic rocks. The most common alteration features are albitization, greisenization and koalinitization. The mass balance calculations of the studied altered samples show enrichments in Zr, Y, Ni, U, Th and Ga and depletions in Zn, Sr, Nb, Ba, Pb, Cu and V. Only the greisenized samples exhibit a significant enrichment in Nb, ∑REE budget and pronounced lanthanide tetrad effect (M-type), especially TE1,4, while weakly expressed tetrad effects are for the other albitized and koalinitized samples. Mineralogically, the common accessory minerals in the altered samples include samarskite-(Y), betafite, uranothorite, zircon, fluorite and cassiterite. The greisenized granites contain high eU and eTh than the other altered types, where they are characterized by an assemblage of the radioactive minerals; samarskite-(Y), betafite, uranothorite in addition to zircon. The inter-element relationships between U and Th and also their ratios illustrate that the radioelement distribution in these granites is mainly governed by magmatic processes, in addition to post-magmatic ones. The distribution of chemical elements and the fractionation of some isovalents within the shear zone are largely controlled by the newly formed mineral phases. With respect to uranium mobilization, uranium migrated from the host alkali feldspar granites of G. Abu Garadi, while the shear zones acted as traps for the migrated uranium. Moreover, U migrated in the shear zone during greisenization and albitization, and migrated out during koalinitization. 相似文献
5.
《Lithos》2007,93(1-2):89-106
The Salvezines Massif in northern French Pyrénées has undergone extensive albitization. The massif consists of gneisses and a leucogranite hosted in Paleozoic sediments (schists and carbonates). The leucogranite was emplaced at the end of the Hercynian orogeny. The granite underwent monazite fractionation during magmatic stages, which induced lowering of REE and Th contents in the most evolved rocks. Hydrothermal alteration during late magmatic stages is also identified through the development of a tetrad effect in the REE patterns of the granite and through the fractionation of ratios like Zr/Hf out of the CHARAC (CHarge RAdius Controlled) range. The granite underwent partial to complete sub-solidus albitization. Progressive metasomatic overprint induced metasomatic replacement of feldspars into albite and dissolution of quartz (episyenitization) together with new albite formation. Hydrothermal muscovite with a sheaf-like structure sometimes crystallised in albitites. Inherited muscovites from magmatic stage and newly formed muscovites from albitites have distinct chemical compositions with the latter being much more phengitic. The initial peraluminous chemistry of the leucogranite was lost during albitization and composition evolved towards a pure albite one (A/CNK = 1). Albitization induced gains in Na and Al, and losses in Si and K. Leaching of REE and U is also identified during albitization, as well as the non-CHARAC behaviour of some elements. δ18O values of quartz and muscovite in albitized granites are in the magmatic range (about 12 and 9.5‰, respectively). Feldspars acquired high δ18O values during albitization (up to 15‰). Muscovite grains from albitites have higher δ18O values than inherited ones and tend towards isotopic equilibrium with albite. The albitizing fluids have interacted with high-δ18O rocks (probably local carbonates) prior to alter granite. Muscovites inherited from magmatic stages display very characteristic disturbed 39Ar–40Ar age spectra with saddle-shapes when a muscovite associated with albitization provided a plateau age at 117.5 Ma for this alteration event. Albitization in the Salvezines Massif just preceded the regional talc/chlorite hydrothermal mineralization. Both events might then represent two outward signs of a huge hydrothermal system at the time of the rotation of the Iberian plate around Europe. The North Pyrenean Metamorphism is identified by 39Ar–40Ar analyses at ca. or younger than 100 Ma. 相似文献
6.
7.
D. Küster 《Mineralium Deposita》1990,25(1):25-33
he Sn-(Nb, Ta) mineralization of the Wamba field (central Nigeria) occurs in muscovite-quartz-microcline pegmatites, which are related to the late-orogenic Pan-African (f 550 Ma) "Older Granites". The emplacement of granites and pegmatites was controlled by late Pan-African shear tectonics. The granitoid magmatism was multiphase and has produced peraluminous biotite granite, biotite-muscovite granite, and muscovite granite plutons. Sodic metasomatism has altered highly evolved granite cupolas and many of the pegmatite dikes. The pegmatitic mineralization of predominantly cassiterite is closely associated with albitization. Chemical data of granites and granitic and pegmatitic muscovites show that Rb, Cs, Sn, Nb, and Ta are enriched during both magmatic and postmagmatic evolution, with highest contents of these elements in early muscovites of the albitized and mineralized pegmatites. Trace-element chemistry of the pegmatitic muscovites reveals a chemical zonation of the pegmatite field related to the late-orogenic shear system. 相似文献
8.
我国主要白云母的矿物学特征研究 总被引：3，自引：1，他引：3
利用X射线荧光光谱分析（XRF）、常规化学分析、X射线光电子能谱分析（XPS）和粉晶X射线衍射分析（XRD）等手段对我国主要白云母进行了系统的矿物学研究，并与印度白云母进行了详细的对比分析，探讨了我国白云母与印度白云母在表丽化学组成和化学态、体栩化学成分、晶体结构方面的差异。研究发现：印度白云母表面K更多地表现为缺失留下空位，表面O严重缺失、不足，四面体层中Si有更多的暴露，表面化学键的不饱和程度高于我国白云母，表现出更高的表面活性。我国主要白云母产地的白云母为2M；型白云母，晶胞参数a、b值随结构中铁和镁离子含遗的增加而增大。 相似文献
9.
《International Geology Review》2012,54(1):13-24
The following topics are discussed: 1) position of, alkalic intrusions in various structural and facies zones of East Tuva and its effect on the composition and form of the intrusions; 2) the close genetic relationship between the alkalic massifs and deep faults, including those approaching that rank. It is demonstrated that fault tectonics and its associated alkalic volcanism control the areal distribution, dimensions, form and structural complexity of the alkalic massifs; also the distribution of autometasomatism, namely albitization, associated with which is the rare-metal mineralization of East Tuva alkalic complex. — Author. 相似文献
10.
Abstract: The northern part of Um Naggat granite massif (UNGM) has suffered extensive post-magmatic metasomatic reworking which results into the development of (Zr, Hf, Nb, Ta, U, Th, F)– and albite-enriched and greisenized apogranite body (UNAP) of 600 m thick, and more than 3 km in the strike length.
Albitization produced an enrichment in Zr (av. 2384 ppm), Hf (61), Nb (419), and U (43). The Th/U ratio ranges between 1. 33 and 1. 90. Extreme albitization (i. e. the albitite rock) is characterized by sharp decrease in the rare metals contents. However, extreme greisenization (i. e. endogreisen bodies) is characterized by a considerable enrichment in Zr (av. 5464 ppm), Hf (143), Nb (2329), Ta (152), U (66) and Th (178). The Th/U ratio ranges between 1. 57 and 3. 60. In contrast to extreme greisenization, it seems that extreme albitization does not apparently change the fluid pH and therefore poor amounts of rare metals are localized in the albitites.
It is suggested that the presence of Na+ , H+ and F- in the ore fluids was essential to stablize complexes of Zr, Hf, Nb, Ta, U, Th, and HREE during extraction and transportation. In contrast, contemporaneous decrease of temperature and increasing pH due to decreasing pressure are considered the essential factors for localization of disseminated mineralization of Zr and Nb in the apical parts of the UNAP. The enhanced uranium content in the alteration facies of UNAP coupled with the absence of significant uranium mineralization may indicate the metalliferous rather than mineralized nature for the UNAP. The high uranium contents are stabilized in refractory accessory minerals. However, with repect to Zr and Nb, the UNAP especially the albitized and greisen facies, can be categorized as a mineralized productive granite. 相似文献
Albitization produced an enrichment in Zr (av. 2384 ppm), Hf (61), Nb (419), and U (43). The Th/U ratio ranges between 1. 33 and 1. 90. Extreme albitization (i. e. the albitite rock) is characterized by sharp decrease in the rare metals contents. However, extreme greisenization (i. e. endogreisen bodies) is characterized by a considerable enrichment in Zr (av. 5464 ppm), Hf (143), Nb (2329), Ta (152), U (66) and Th (178). The Th/U ratio ranges between 1. 57 and 3. 60. In contrast to extreme greisenization, it seems that extreme albitization does not apparently change the fluid pH and therefore poor amounts of rare metals are localized in the albitites.
It is suggested that the presence of Na
11.
南岭区域不同时期花岗岩体及与其有关的稀有金属矿床的形成,除了受区域混合岩化作用以及区域花岗岩浆分异演化作用的制约外,还受到遍布于南岭区域的每一个多期多阶段复式花岗岩体的自身分异演化作用的深刻的影响。在那些复式岩体中,只有在岩体分异演化的晚期阶段,才会出现稀有金属花岗岩母岩。现仅将本区域复式岩体和成矿母岩的分异演化及其与成矿作用的关系论述如下。 相似文献
12.
内蒙锡林浩特石灰窑铌钽矿床是我国最近发现的一处大型稀有金属矿床.通过详细分析该矿床地质特征、控矿因素及其成因,主要获得如下认识:1)该矿床矿石属于碱性花岗岩系列;2)矿石中的铌钽矿物主要包括铌锰矿、铌钽铁矿、铌钽锰矿、锡锰钽矿和细晶石;3)该矿床可能是前期花岗岩岩浆结晶和后期热液交代综合作用的产物,热液交代是铌钽铷主要成矿阶段;4)从铌钽铷矿化成因和富集规律可知,金属矿化与钠长石化、云英岩化密切相关,且矿体赋存于蚀变花岗岩中,分布上严格受北东向构造的控制,因此,钠长石化、云英岩化的花岗岩是寻找上述稀有金属的直接找矿标志,同时石灰窑燕山早期花岗岩出露地段很可能是寻找稀有金属矿的有希望地区;5)围绕石灰窑花岗岩主岩体周围寻找晚期侵位的钠长石化花岗岩小岩体的隆起和浅部部位,是寻找钽铌铷矿的基本思路. 相似文献
13.
对利用ASTER、RapidEye、QuickBird及ASAR等多种类型遥感影像在伟晶岩型矿床遥感找矿中的综合应用进行了探讨。云英岩化和钠长石化是阿祖拜矿田两类主要的蚀变类型。在分析其光谱特征的基础上,确定了利用ASTER数据对这两类蚀变进行信息提取的方法。利用ASTER热红外数据进行了岩浆岩类型的划分,为不同岩性接触带的准确定位提供了依据。伟晶岩在可见光-近红外光谱段的高反射率是伟晶岩的自动识别及遥感解译重要的物理基础。以QuickBird的伟晶岩解译结果为检验标准,得到RapidEye的伟晶岩自动提取精度约86%。构造交汇部位、岩性接触带以及伟晶岩富集区与蚀变异常的叠加部分是该区成矿预测的重要依据。基于蚀变异常、伟晶岩富集区、地质构造等遥感找矿综合信息,圈定了4个远景成矿靶区,为进一步开展地质详查工作提供参考。关键词:伟晶岩;蚀变异常;遥感;信息提取;成矿预测 相似文献
14.
《International Geology Review》2012,54(6):814-827
This study is concerned with formation of minerals containing Li, Be, Cb, Ta, W, Bi, and other elements. The distribution of 35 accessory minerals was examined in biotite granite massifs occupying an area of 10 km2 . These minerals formed during the late magmatic stage and mainly during the subsequent metasomatic processes, such as rnuscovitization, early albitization, greisenization, late albitization, and microclinization. Tantalum and columbium mineralization is associated with rocks intensely altered by the processes of alkaline metasomatism and reflects differentiation of rare earth's mineralization in marginal granite massifs. Minerals containing Be, W, Bi, Sn, and Mo were deposited during the acidic stage of metasomatism. The subsequent alkaline stage of metasomatism resulted in leaching of these elements and their redeposition outside the massif. The paper is of interest as a guide in prospecting for tantalum and columbium in granitic intrusions.--E. A. Alexandrov. 相似文献
15.
赣北大湖塘钨矿成岩成矿物质来源的矿物学和同位素示踪研究 总被引：9，自引：3，他引：6
赣北大湖塘超大型钨矿位于九岭钨多金属矿集区东部。本文对大湖塘钨矿石门寺矿段矿物学特征进行了系统的研究,结合同位素示踪分析了成岩成矿物质来源。岩相学研究表明,石门寺矿段蚀变以黑云母化、云英岩化及碱交代(钾长石化、钠长石化)作用为主。黑云母化的过程中释放了一定量的挥发分,云英岩化和碱交代作用除萃取部分的成矿物质外,使岩体中的Ca2+大量活化迁移。晋宁晚期黑云母花岗闪长岩与燕山中期似斑状花岗岩、花岗斑岩矿物成分研究表明:(1)斜长石普遍富钠,似伟晶岩壳主晶为钾长石,客晶为钠长石;(2)黑云母具有富铁贫镁的特点,黑云母花岗闪长岩及似斑状花岗岩中的黑云母均为铁质黑云母,花岗斑岩中黑云母为铁叶云母。黑云母成分指示大湖塘石门寺矿段花岗岩类均为过铝质S型花岗岩,成岩物质均为壳源。石英氢、氧同位素及黑钨矿氧同位素研究表明成矿流体为岩浆水。黄铜矿、辉钼矿硫同位素表明成矿流体中硫来自于岩浆。结合前人研究成果,本文认为富钨的双桥山群浅变质岩在燕山中期发生了部分熔融,产生了高分异的富含钨元素及挥发分的岩浆,岩浆分异演化过程中形成的含矿热液使侵入体自身及围岩发生大规模的蚀变作用,进而在燕山中期侵入岩的内外接触带形成了大湖塘超大型钨多金属矿床。 相似文献
16.
湖南上堡矿区钨锡矿成矿条件及找矿前景分析 总被引：1，自引：0，他引：1
上堡矿区出露地层有石炭系和二叠系,壶天群及栖霞组的灰岩、白云质灰岩化学性质活泼.W、Sn含量较高;区内的燕山早期黑云母花岗岩呈岩株或岩枝状产出,岩石具钠长石化和云英岩化,微量元素丰度值高;花岗岩体顶面的洼部构造很发育,规模大,是有利的成矿空间;围岩蚀变强烈,以矽卡岩化为主;W、Sn等元素的土壤异常围绕岩体分布,并且强度大,范围广;经钻探揭露,在接触带上有具工业意义的矽卡岩型钨锡矿体.通过分析,认为上堡矿区成矿地质条件优越,具有大型规模钨锡矿找矿潜力. 相似文献
17.
Dušan Němec 《Mineralium Deposita》1990,25(4):297-303
In the central Iron Mountains the ore-mineralized deformation zones represent deep reaching faults which possibly reach the upper mantle. During geological history they were used by ascending magmas, fluids, and barren and ore hydrothermal solutions. It can be shown that the metasomatism provoked by acid fluids bears the character of greisenization. The type of the original greisenized rocks here can be determined on the basis of elements that were immobile during greisenization, especially Si, Ti, Sc and REE. After or even during greisenization, the metasomatic rocks were affected by shearing metamorphism corresponding in its PT conditions to the middle zone of the almandine-amphibolite facies. It was possibly in this period that the enigmatic skarn body of Samaov originated. Owing to its similarity to the dyke skarn of Kraskov, its similar origin could be assumed: the deposition of skarn minerals from circulating fluids, which were perhaps released during greisenization. 相似文献
18.
华南与燕山期花岗岩有关的稀土、稀有、有色金属矿床成矿系列 总被引：19，自引：4，他引：19
本文所述及的地区在地质构造上属黄汲清先生所划分的华南加里东褶皱带的范围。该区在下古生代时期为冒地槽,志留纪时发生加里东运动,褶皱隆起,结束了地槽阶段。加里东运动之后,此区仍不断经受构造运动,成为比较典型的构造活化区。主要表现为:在海西时期一些地带强烈断陷,堆积了巨厚的沉积物,如湘南、河池—南丹等地区;印支—燕山时 相似文献
19.
《International Geology Review》2012,54(10):1208-1214
An attempt at energy (heat) analysis of greisenization is made on the basis of determining the solution and specific heat of the original rocks and their metasomatites. A great amount of heat is released in greisenization; metasomatic zones are formed with the energy level lower than in the original rocks. -- Author. 相似文献
20.
《International Geology Review》2012,54(10):1144-1153
The geochemical features of hydrothermal-pneumatolytic rare element deposits are discussed on the basis of a natural connection between high temperature metasomatism phenomena and concentration processes of some rare elements. Two kinds of metasomatic processes are most interesting from the view-point of rare elements (albitization and greisenization). Li and Rb are concentrated in zinnwaldite-bearingalbitized granites and greisens. Nb, Ta (in columbite, pyrochlore, microlite, hatchettolite), Zr (in malacone zyrtolite), Be (beryl) are concentrated in albitized and greisenized granites. The beryllium deposits are closely connected with greisens of different composition, and quartz-greisen veins. The fluorite-bearing metasomatic rocks among carbonate rocks are characterizedby accumulations of Be (chrysoberyl, phenacite, taateite, sianhualite), Li (Li - margarite), Sn (cassiterite). The character of postmagmatic alterations of intrusive and wall rocks is a valuable indicator of the possibility of concentration of different rare elements.—Auth. English Summary. 相似文献