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1.
广西大厂层状花岗质岩石地质、地球化学特征及成因初探 总被引：1，自引：0，他引：1
在广西大厂拉么矿区黑云母花岗岩岩体周围的层状花岗质岩石,其地质产状、成岩时代、结构构造、矿物成分、化学成分及稀土元素、微量元素地球化学特征等方面与一般的交代岩不同,也与一般的岩浆成因花岗岩不同;成岩物质既有岩浆来源又有地层来源,反映了与笼箱盖岩体同源的岩汁或热液沿层交代泥盆系的成因特征。它与层状锡多金属矿体、层状夕卡岩及层状锌-铜矿体等共同构成燕山期酸性岩浆作用所形成的层状交代体系。 相似文献
2.
关于稀有金属花岗岩的成矿流体来源及与岩浆演化的成因关系长期存疑。现以华南稀有金属花岗岩的典型代表广西栗木花岗岩为例,通过对成矿地质体花岗岩垂向分带的岩相学特征及矿床地质特征的深入研究,分析岩浆—热液的形成演化路径与成矿过程。研究表明,岩浆演化除了结晶作用外,还有大规模的气—液分离,岩浆—热液的形成主要与其中的气—液分离有关,不是传统意义上的岩浆残液。不同成因类型矿床的成矿流体均来自第二次气—液分离形成的二级残余富气流体相构成的岩浆—热液,岩浆—热液系统由三个不同空间分布的分支系统组成,每个分支系统在不同环境下以交代、结晶等不同形式与上部地质体作用,演化形成成矿流体,最后形成岩体接触带及附近的不同成因类型的矿床和以细晶岩为底部边界的成分分带。研究成果还原了岩浆演化形成岩浆—热液的详细路径,构建了成矿模型,对深入认识花岗岩的岩浆演化与成岩成矿作用具有启示意义。 相似文献
3.
关于稀有金属花岗岩的成矿流体来源及与岩浆演化的成因关系长期存疑。现以华南稀有金属花岗岩的典型代表广西栗木花岗岩为例,通过对成矿地质体花岗岩垂向分带的岩相学特征及矿床地质特征的深入研究,分析岩浆—热液的形成演化路径与成矿过程。研究表明,岩浆演化除了结晶作用外,还有大规模的气—液分离,岩浆—热液的形成主要与其中的气—液分离有关,不是传统意义上的岩浆残液。不同成因类型矿床的成矿流体均来自第二次气—液分离形成的二级残余富气流体相构成的岩浆—热液,岩浆—热液系统由3个不同空间分布的分支系统组成,每个分支系统在不同环境下以交代、结晶等不同形式与上部地质体作用,演化形成成矿流体,最后形成岩体接触带及附近的不同成因类型的矿床和以细晶岩为底部边界的成分分带。研究成果还原了岩浆演化形成岩浆—热液的详细路径,构建了成矿模型,对深入认识花岗岩的岩浆演化与成岩成矿作用具有启示意义。 相似文献
4.
通过对印尼某铁矿区岩浆岩与磁铁矿关系的研究,认为该区主花岗岩体是成矿物质的主要来源;接触交代型是矿区主要成矿类型;正长细晶岩是主花岗岩体成岩后期残余岩浆充分结晶分异的产物;正长细晶岩与花岗岩之间及其内部赋存的磁铁矿在成因上属接触交代型磁铁矿经后期残余气液充填交代叠加所形成. 相似文献
5.
甘肃西成地区层状的花岗质岩脉地质地球化学特征及其与金矿关系 总被引：4，自引：0，他引：4
西成地区小沟里和三洋坝金矿区发育层状的花岗质岩脉带，其成岩物质既有岩浆热液来源又有地层来源，反映了海西期秦岭裂谷扩张时岩浆热液顺层交代泥盆系岩层的成因特征；层状的花岗质岩脉与石英钠长岩等共同构成了西成地区泥盆纪热液交代，热水沉积所形成的层状交代沉积岩系；层状的岩脉与金矿床的空间关系密切是寻找金矿床的有效岩石标志。 相似文献
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8.
羊拉地区含矿夕卡岩流体包裹体特征及其成因意义带 总被引：8，自引：2，他引：6
羊拉铜矿化集中区共有４个夕卡岩体,按成因分为喷流－沉积和接触交代夕卡岩两大类,前者呈层状,是铜的主要赋矿围岩。层状夕卡岩中包裹体以类型多、组分复杂、均一温度（１００～６２０℃,一般大于３００℃）和盐度（８．３％～５５．０％ＮａＣｌ,一般≥２０％ＮａＣｌ）高且变化范围大、密度高（一般大于１．００ｇ／ｃｍ３）、捕获压力低（１０～２５ＭＰａ）为特征;交代夕卡岩则以包裹体类型简单、组分单一、均一温度（一般小于２５０℃）和盐度中—低（９．０％～２０．０％ＮａＣｌ）、密度低（一般小于１．００ｇ／ｃｍ３）且变化范围大、捕获压力高（１５０ＭＰａ）为特征。这些包裹体特征反映了两类夕卡岩的流体来源和演化机制是不同的,其中层状夕卡岩之流体为深部源与海水源的二元混合特征;交代夕卡岩为岩浆（体）源等组分自然冷却演化趋势。 相似文献
9.
海坨山岩体位于北京市延庆区与河北省怀来县的交界处,为一大型复式岩基,前人对于其成因类型及形成环境方面的研究程度较低。黑云母是花岗岩中最为常见的暗色造岩矿物之一,其化学成分对生长环境较为敏感,可提供熔体的物理化学条件等信息,反映岩浆演化和结晶条件,故研究岩体中黑云母的成分特征,对研究其岩浆物质来源,分析其岩浆形成环境,探讨其与成岩作用的关系具有很好的指示意义。本文通过电子探针方法,对海坨山岩体中黑云母的化学成分特征进行了分析和研究,并在此基础上,对该岩体的岩浆物质来源与形成环境条件进行了研究与探讨。研究显示,海坨山岩体中的黑云母,具有富铁、镁,贫硅、铝的特征,钛的含量较高,属于镁质黑云母。其成分特征表明,海坨山岩体属I型花岗岩,其岩浆物质来源于上地幔与下地壳,形成于相对高温高压的较深环境。 相似文献
10.
南岭是中国重要的钨锡多金属成矿带。岩浆活动及成矿作用具有多阶段性的特点，成岩成矿作用具有统一的地质背景及构造应力场。陆壳重熔型花岗岩类不同成岩阶段具有极为一致的稀土元素分布模式，暗示它们的定位和冷却都是在深部同源岩浆分异事件中形成的；岩石和矿石稀土球粒陨石标准化曲线有着相似的变化特征，反映成矿与岩浆活动有着密切的成因联系，物质来源上具有一致性；矿石硫化物和岩石长石Pb同位素组成相近，显示成岩成矿物质有明显的亲缘关系。结合多数情况下矿脉切穿已固结岩体的地质事实，推测燕山中期陆壳重熔型花岗岩类成岩成矿物质主体来自深部同一岩浆源区，为同源岩浆分异演化不同阶段的产物；燕山晚期花岗质火山-侵入杂岩与相关锡铀矿化空间上密切伴生，物质来源也具同源性。典型复式岩体同源岩浆不同阶段侵位及相匹配的成矿作用时差一般小于10．0Ma，集中在0～8．0Ma。结合华南中生代岩石圈多次伸展活动的区域背景及矿床（田）地质特征，推测南岭地区的多阶段成岩成矿作用是脉动式构造演化的产物，成岩成矿物质来自深部同一岩浆房的不同演化阶段。 相似文献
11.
S. Viswanathan 《Lithos》1974,7(1):29-34
Oxygen isotope studies of granitic rocks from the 2.7 b.y.-old composite Giants Range batholith show that: (1) δ(O18)quartz values of 9 to 10 permil characterize relatively uncontaminated Lower Precambrian, magmatic granodiorites and granites; (2) granitic rocks thought to have formed by static granitization have δ(O18)quartz values that are 1 to 2 permil higher than magmatic granitic rocks; (3) satellite leucogranite bodies have values nearly identical to those of the main intrusive phases even where they transect O18-rich metasedimentary wall rocks; (4) oxygen isotopic interaction between the granitic melts and their O18-rich wall rocks was minimal; and (5) O18/O18 ratios of quartz grains in a metasomatic granite are largely inherited from the precursor rock, but during the progression — sedimentary parent → partially granitized parent → metasomatic granite → there is gradual decrease in δ(O18)quartz by 1 to 2 permil. 相似文献
12.
Muhammad Saleem Mughal Muhammad Sabir Khan Muhammad Rustam Khan Sohail Mustafa Fahad Hameed Muhammad Basharat Abrar Niaz 《Arabian Journal of Geosciences》2016,9(8):528
Late Proterozoic rocks of Tanol Formation in the Lesser Himalayas of Neelum Valley area are largely green schist to amphibolite facies rocks intruded by early Cambrian Jura granite gneiss and Jura granite representing Pan-African orogeny event in the area. These rocks are further intruded by pegmatites of acidic composition, aplites, and dolerite dykes. Based on field observations, texture, and petrographic character, three different categories of granite gneiss (i.e., highly porphyritic, coarse-grained two micas granite gneiss, medium-grained two micas granite gneiss, and leucocratic tourmaline-bearing muscovite granite gneiss), and granites (i.e., highly porphyritic coarse-grained two micas granite, medium-grained two micas granite, and leucocratic tourmaline-bearing coarse-grained muscovite granite) were classified. Thin section studies show that granite gneiss and granite are formed due to fractional crystallization, as revealed by zoning in plagioclase. The Al saturation index indicates that granite gneiss and granite are strongly peraluminous and S-type. Geochemical analysis shows that all granite gneisses are magnesian except one which is ferroan whereas all granites are ferroan except one which is magnesian. The CaO/Na2O ratio (>0.3) indicates that granitic melt of Jura granite gneiss and granite is pelite-psammite derived peraluminous granitic melt formed due to partial melting of Tanol Formation. The rare earth element (REE) patterns of the Jura granite and Jura granite gneiss indicate that granitic magma of Jura granite and Jura granite gneiss is formed due to partial melting of rocks that are similar in composition to that of upper continental crust. 相似文献
13.
西秦岭党川花岗岩基的岩石化学特征 总被引：1，自引：0，他引：1
党川花岗岩基产于祁连与北秦岭造山带结合部位,由9个岩体组成,岩石普遍富K2O。志留纪为闪长岩-石英闪长岩,显著贫SiO2、Na2O,显著富MgO、CaO、TFeO、MnO、P2O5。泥盆纪-侏罗纪岩体为二长-正长花岗岩类,各岩体岩石化学特征较相似,高TiO2、K2O、Na2O,贫MgO、CaO,显示继承性演化规律。志留纪岩体的岩石化学构造环境判别及与其共生的早古生代火山岩相配套,是俯冲造山过程中的岛弧闪长岩类,而泥盆纪熊山沟岩体则是与之密切有关的造山期后陆缘或弧后花岗岩类。其余各岩体是本区造山后与大陆抬升作用以及大陆裂谷作用有关的花岗岩类。 相似文献
14.
Osama M. K. Kassem 《Geotectonics》2011,45(3):244-254
Finite-strain was studied in the mylonitic granitic and metasedimentary rocks in the northern thrust in Wadi Mubarak belt
to show a relationship to nappe contacts between the old granitic and metavolcano-sedimentary rocks and to shed light on the
heterogeneous deformation for the northern thrust in Wadi Mubarak belt. We used the Rf/ϕ and Fry methods on feldspar porphyroclasts, quartz and mafic grains from 7 old granitic and 7 metasedimentary samples in
the northern thrust in Wadi Mubarak belt. The finite-strain data shows that old granitic rocks were moderate to highly deformed
and axial ratios in the XZ section range from 3.05 to 7.10 for granitic and metasedimentary rocks. The long axes (X) of the
finite-strain ellipsoids trend W/WNW and E/ENE in the northern thrust in Wadi Mubarak belt. Furthermore, the short axes (Z)
are subvertical associated with a subhorizontal foliation. The value of strain magnitudes mainly constants towards the tectonic
contacts between the mylonitic granite and metavolcano-sedimentary rocks. The data indicate oblate strain symmetry (flattening
strain) in the mylonitic granite rocks. It is suggested that the accumulation of finite strain was formed before or/and during
nappe contacts. The penetrative subhorizontal foliation is subparallel to the tectonic contacts with the overlying nappes
and foliation was formed during nappe thrusting. 相似文献
15.
R. Machado C. Lana G. Stevens C.R.S. Filho W.U. Reimold Iain McDonald 《Geochimica et cosmochimica acta》2009,73(23):7183-7201
This paper provides important insights into the generation, extraction and crystallization of clast-laden impact melt rocks from the Araguainha impact structure, central Brazil. Despite the mixed nature of the Araguainha target rocks (comprising a 2 km thick sequence of sedimentary rocks and underlying granitic basement), the exposed melt bodies are characterised by an alkali-rich granitic matrix embedding mineral and rock fragments derived only from the target granite. The melt rocks occur in the form of a massive impact melt sheet overlying the eroded central uplift structure, and as melt veins in the granite of the core of the central uplift. Bulk-rock major and trace element data (including platinum group elements) indicate that the precursor melts were generated locally, principally by partial melting of the target granite, without any contribution from the sedimentary sequence or the projectile. The dense network of melt veins was formed in isolation, by selective melting of plagioclase and alkali feldspar within the granite target. Plagioclase and alkali feldspar melted discretely and congruently, producing domains in the matrix of the melt veins, which closely match the stoichiometry of these minerals. The compositionally discrete initial melt phases migrated through a dense network of microfractures before being assembled into larger melt veins. Freezing of the melt veins was substantially fast, and the melt components were quenched in the form of alkali-feldspar and plagioclase schlieren in the matrix of the melt veins. The overlying impact melt rock is, in contrast, characterised by a granophyric matrix consisting of albite, sanidine, quartz, biotite and chlorite. In this case, melt components appear to have been more mobile and to have mixed completely to form a granitic parental melt. We relate the melting of the minerals to post-shock temperatures that exceeded the melting point of feldspars. 相似文献
16.
This paper reviews recent progress on the geotectonic evolution of exotic Paleozoic terranes in Southwest Japan, namely the Paleo-Ryoke and Kurosegawa terranes. The Paleo-Ryoke Terrane is composed mainly of Permian granitic rocks with hornfels, mid-Cretaceous high-grade metamorphic rocks associated with granitic rocks, and Upper Cretaceous sedimentary cover. They form nappe structures on the Sambagawa metamorphic rocks. The Permian granitic rocks are correlative with granitic clasts in Permian conglomerates in the South Kitakami Terrane, whereas the mid-Cretaceous rocks are correlative with those in the Abukuma Terrane. This correlation suggests that the elements of Northeast Japan to the northeast of the Tanakura Tectonic Line were connected in between the paired metamorphic belt along the Median Tectonic Line, Southwest Japan. The Kurosegawa Terrane is composed of various Paleozoic rocks with serpentinite and occurs as disrupted bodies bounded by faults in the middle part of the Jurassic Chichibu Terrane accretionary complex. It is correlated with the South Kitakami Terrane in Northeast Japan. The constituents of both terranes are considered to have been originally distributed more closely and overlay the Jurassic accretionary terrane as nappes. The current sporadic occurrence of these terranes can possibly be attributed to the difference in erosion level and later stage depression or transtension along strike-slip faults. The constituents of both exotic terranes, especially the Ordovician granite in the Kurosegawa-South Kitakami Terrane and the Permian granite in the Paleo-Ryoke Terrane provide a significant key to reconstructing these exotic terranes by correlating them with Paleozoic granitoids in the eastern Asia continent. 相似文献
17.
Dilip K Mukhopadhyay Bidyut K Bhadra Tamal K Ghosh Deepak C Srivastava 《Journal of Earth System Science》1996,105(2):157-171
Numerous peraluminous and porphyritic granitic bodies and augen gneisses of granitic compositions occur in the nappe sequences
of the Lower Himalaya. They are Proterozoic-to-lower Paleozoic in age and have been grouped into the ‘Lesser Himalaya granite
belt’. The mode of emplacement and tectonic significance of these granites are as yet uncertain but they are generally considered
to be sheet-like intrusions into the surrounding rocks. The small and isolated granite body (the Chur granite) that crops
out around the Chur peak in the Himachal Himalaya is one of the more famous of these granites. Several lines of evidence have
been adduced to show that the Chur granite has a thrust (the Chur thrust) contact with the underlying metasedimentary sequence
(locally called the Jutogh Group). The Chur granite with restricted occurrence at the highest topographic and structural levels
represents an erosional remnant of a much larger sub-horizontal thrust sheet. The contact relations between the country rocks
and many of the other granite and granitic augen gneisses in the Lesser Himalaya belt are apparently similar to that of the
Chur granite suggesting that at least some of them may also represent thrust sheets. 相似文献
18.
M. Owada Y. Osanai N. Nakano T. Matsushita Tran Ngoc Nam T. Tsunogae T. Toyoshima Pham Binh H. Kagami 《Gondwana Research》2007,12(4):428-437
Asia grew in the Late Permian by the collision of a number of micro-continents. Syn- to post-collisional magmatism occurred along the continental collision zones . In this study, we report two types of granitic rocks, garnet granite (Grt granite) and orthopyroxene granite (Opx granite), from the Kontum massif, central Vietnam, which is situated on the continental collision zone between the South China and Indochina cratons. These granitic rocks were formed at ca. 250 Ma when high-temperature (HT) and ultrahigh-temperature (UHT) metamorphism took place in the same zone. Based on the petrological and geochemical features compared with previously reported experimental results, garnet-bearing granite is derived from pelitic gneisses by partial melting, whereas orthopyroxene-bearing granite is produced by the partial melting of garnet-bearing mafic granulites. We inferred that a significantly high-geothermal gradient is required to produce Vietnamese granitic magmatism and related HT to UHT metamorphism. This geotherm may be attributed to upwelling mantle plume beneath the Kontum massif during the Late Permian. 相似文献