浙东白垩纪北漳和梁弄花岗岩体及其暗色岩石包体研究

浙东地区晚中生代花岗岩类在岩性上分为三类：花岗岩-二长花岗岩、钾长花岗岩和A型花岗岩。对后两类花岗岩已有较多研究,但对前一类,尤其是二长花岗岩的研究还较薄弱。选择浙东具代表性的北漳和梁弄二长花岗岩体及其所含暗色岩石包体,以及共生的石英闪长岩类,通过系统的岩石学与地球化学对比研究,提出浙东二长花岗岩属准铝质、高钾钙碱性Ⅰ型花岗岩类演化系列,暗色岩石包体是由花岗质岩浆在深部析离出的镁铁质微粒包体(MME),成分特征类似于石英闪长岩,说明三者具内在成因联系,均与俯冲作用关系密切。     

Petrologic significance of rare earths distribution in granites

Granitic rocks of various ages and composition are found in the Schwarzwald region of West Germany. These granites range in age from Upper Devonian to Upper Carboniferous (370-280 m.y.) and in composition from granodiorites to alkali feldspar granites. 14 representative samples of twelve different types were analysed for their La, Ce, Nd, Sm, Eu, Tb, Dy, Yb, Lu by instrumental neutron activation. The studies reveal that there are characteristic differences between the different types of granitic rocks both as regards to their total REE content as well as the distribution pattern of these elements. These differences can not be directly related to the variations in the major element chemistry or the mineralogy of the granites. On the other hand, a relationship is found between the age of the granitic rocks and the total REE as well as their distribution pattern. In general the ΣREE varies from 22 to 215 ppm in different types. The ΣLa-Lu increases gradually in the direction Upper Devonian→Lower Carboniferous, however, in the granitic rocks of the Upper Carboniferous this trend is reversed and there is again a marked depletion in the content of REE. The chondrite normalised patterns of all the older types give a smooth concave curve with decrease of concentration from La to Lu. All the Upper Carboniferous granites on the other hand are characterised by a progressive pronounced negative Eu anomaly. The gradual increase of the ΣREE in the older granites is related to their evolution by progressive anatexis, whereas, the decrease in the total REE content in case of the younger Upper Carboniferous granites is due to processes of magmatic differentiation. The depletion of Eu in these K-feldspar rich types of granite is probably related to the breakdown of biotite in the anatectic starting material.     

黑龙江秋皮沟铜矿床年代学与地球化学特征及成因

秋皮沟矿床位于小兴安岭-张广才岭成矿带延寿矿集区。在野外地质调查的基础上开展了锆石 LA--ICP--MS U--Pb 法测年、主量与微量元素测试。测试结果显示,主量元素中Ca、Ti、Al、Si 等在花岗岩、矽卡岩和大理岩间发生了迁入和迁出,含量呈线性变化关系。成矿岩体花岗岩属过铝质钙碱性系列花岗岩( A/CNK = 1. 26,Na2O/K2O = 0. 93,σ = 1. 27) ; 富集Rb、Th、U、Nd 等元素,亏损Sr、 P、Ti,具有与俯冲带岩浆岩地球化学相似的特征。各样品稀土配分模式轻稀土( LREE) 富集,重稀土( HREE) 亏损,具轻微的Eu 负异常,其相似的REE 配分模式表明它们在成因上具内在联系。花岗岩锆石U--Pb 谐和年龄184. 1 ± 2. 2 Ma,属于早侏罗世。秋皮沟矿床的形成晚于184. 1 ± 2. 2 Ma,可能与太平洋板块俯冲有关。     

云南个旧双竹锡—铜多金属矿床地质特征及成矿规律

本文总结了双竹锡-铜多金属矿床地质特征、成矿规律及其与花岗岩的关系.(晚期富挥发分分异作用和蚀变有关).接触交代矿床与花岗岩的突起和凹部有密切关系,并与围岩物理化学特征有关.     

High- and Low-Temperature I-type Granites

Abstract: I– and S-type granites differ in several distinctive ways, as a consequence of their derivation from contrasting source rocks. The more mafic granites, whose compositions are closest to those of the source rocks, are most readily classified as I– or S–type. As granites become more felsic, compositions of the two types converge towards those of lowest temperature silicate melts. While discrimination of the two is therefore more difficult for such felsic rocks, that in no way invalidates the twofold subdivision. If felsic granite melts undergo fractional crystallisation, the major element compositions are not affected to any significant extent, but the concentrations of trace elements can vary widely. For some trace elements, fractional crystallisation causes the trace element abundances to diverge, so the I– and S– type granites are again easily separated. Such fractionated S-type granites can be distinguished, for example, by high P and low Th and Ce, relative to their I-type analogues. Our observations in the Lachlan Fold Belt show that there is no genetic basis for subdividing peraluminous granites into more mafic and felsic varieties, as has been attempted elsewhere. The subdivision of felsic peraluminous granites into I– and S-types is more appropriate, and mafic peraluminous granites are always S–type. In a given area, associated mafic and felsic S-type granites are likely to be closely related in origin, with the former comprising both restite-rich magmas and cumulate rocks, and the felsic granites corresponding to melts that may have undergone fractional crystallisation after prior restite separation. We propose a subdivision of I-type granites into two groups, formed at high and low temperatures. The high-temperature I–type granites formed from a magma that was completely or largely molten, and in which crystals of zircon were not initially present because the melt was undersaturated in zircon. In comparison with low-temperature I–type granites, the compositions extend to lower SiO₂ contents and the abundances of Ba, Zr and the rare earth elements initially increase with increasing SiO₂ in the more mafic rocks. While the high-temperature I–type granite magmas were produced by the partial melting of mafic source rocks, their low-temperature analogues resulted from the partial melting of quartzofeldspathic rocks such as older tonalites. In that second case, the melt produced was felsic and the more mafic low-temperature I–type granites have that character because of the presence of entrained and magmatically equilibrated restite. High temperature granites are more prospective for mineralisation, both because of that higher temperature and because they have a greater capacity to undergo extended fractional crystallisation, with consequent concentration of incompatible components, including H₂O.     

阿拉善宗乃山岩体东南缘花岗岩LA-ICP-MS锆石U-Pb年龄与地球化学特征

阿拉善宗乃山岩体东南缘分布多种类型的花岗岩,本文主要采用岩相学、激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)锆石U-Pb定年、岩石地球化学等技术手段,对宗乃山岩体东南缘岩石类型、年代学、源岩特征以及构造背景进行了研究。结果表明:岩石类型主要为碱性-钙碱性准铝质花岗岩和闪长岩;单颗粒锆石分析获得黑云母斜长花岗岩年龄为236.8±1.9 Ma~249.7±2.6 Ma,片麻状花岗岩年龄为268.1±1.1 Ma,岩体成岩时期主要为华力西晚期和印支期早期,具有多期侵入的特征。该岩体岩石源岩为I型花岗岩,源于地壳火山弧区和同碰撞区,表明由于洋壳俯冲作用,在宗乃山东南缘形成了岛弧花岗岩侵入体。LA-ICP-MS锆石U-Pb定年技术为洋壳俯冲提供了年代学约束,确定了研究区碰撞时间为早于236.8±1.9 Ma。     

湖北麻城市四道河地区面理化含榴花岗岩的成因

野外和室内研究结果表明,四道河地区面理化含榴花岗岩由古生代沉积岩变质而成。在元素地球化学特征上,具有与岩浆成因的碱性花岗岩一致的特点:高硅(SiO2=75.24%～77.23%)、富碱(Na2O+K2O=6.87%～8.84%)、低铝(Al2O3=11.00%～12.78%);富Rb、Ba、Th、U等大离子亲石元素和Pb,贫Nb、Ta、Zr、Hf等高场强元素;稀土元素含量较高(∑REE=101.08～180.1μg/g),轻稀土元素相对富集(LREE/HREE=3.1～6.8),铕有中等负异常(δEu=0.30～0.68);锆石成因类型及定年结果表明,老核(继承锆石)是异地多时代(元古代-古生代),其寄主岩的原岩是沉积岩,时代不会早于古生代。     

新疆阿拉套山花岗岩类的岩石化学

新疆阿拉套山南坡东西向展布的花岗岩石的岩石化学研究表明，本区同时存在Ｉ型和Ｓ型两种类型的花岗岩，其分布受构造环境控制，靠近古板块缝合线为Ｉ型花岗岩分布区、远离古板块缝合线为Ｓ型花岗岩分布区。源岩性质和作用强弱等因素可能是造成岩石化学成分差异的原因。     

Rare earth elements in granitic rocks

The younger granites in Finland contain more REE than the older ones. In the youngest, postorogenic rapakivi granites, the total REE concentration is highest, the light REE are more enriched, and the negative Eu anomaly is more pronounced than in the older granites. The enrichment of the light REE, the anomalous behavior of the extreme elements (La, Ce, and Lu) in normalized graphs, and the depletion of Eu indicate the degree of differentiation the rock has undergone. These features are usually more pronounced in large, homogeneous granites than in metamorphic or volcanogenic rocks. Silicic vein rocks usually contain less REE than the granites proper; the distribution pattern in many is as in granites, but in some the heavy elements are more enriched. The positive Eu anomaly in Precambrian metamorphic rocks is tentatively attributed to metamorphic differentiation and to the secretion of silicic material from the host rock.     

The high-K diorites and associated rocks of the Yeoval diorite complex,N.S.W.

Field relationships, petrography and chemistry (including selected trace elements) of an occurrence of high-K diorite from Yeoval, N.S.W., Australia, are described. The Yeoval diorite complex is a calc-alkaline suite of rocks ranging from gabbros through diorites to granites with an association of fine-grained types. The dominant type of diorite is high in potassium (>2% K₂O) and their classification is based mainly on chemical data rather than conventional petrography. As such the high-K diorites may be correlated with the high-K andesites of orogenic regions. Comparisons with occurrences of high-K andesites are made. Data are presented to show that the gabbros and diorites are genetically related whereas no relation between the diorites and granites can be established.     

东昆仑造山带三叠纪岩浆混合成因花岗岩的岩浆底侵作用机制

东昆仑造山带广泛出露三叠纪岩浆混合成因花岗岩，它们具有共同的特征：岩体成分变化大；花岗岩类岩石中富含镁铁质微粒包体（mafic microgranular enclave--MME）；不同岩性之间常常呈渐变过渡关系。同时，这些岩体无一例外都和代表下地壳的深变质岩共生，暗示岩浆就位于地壳深部。此外，东昆仑地区广泛发育基性侵入体，它们产在深变质岩中，或者与岩浆混合成因花岗岩类共生，暗示下地壳物质的部分熔融和岩浆混合成因花岗岩的形成有可能与基性岩浆底侵作用有关。笔者选择东昆仑加鲁河这一典型的岩浆混合成因花岗岩体为例，对其岩石学、地球化学、同位素地球化学等特征进行了详细研究，认为幔源岩浆底侵作用是这类岩体形成的直接原因，并对幔源岩浆底侵作用和岩浆混合成因花岗岩之间的成因联系以及幔源岩浆底侵作用在东昆仑造山带三叠纪地壳生长和构造演化中所起的重要作用进行了讨论，构建了加厚陆壳背景下的断离-底侵-混合-拆沉作用模型。     

岩石中金和铅在热液流体中的浸出实验研究

我国北方金矿主要受变质岩,花岗岩和构造条件控制,即一般公认的“三位一体”的成矿模式,但成矿元素是由花岗岩还是变质岩提供的则是值得进一步研究的问题。此外,各金矿通常伴有铝的分散晕,且铅同位素组成在区域上多成线性展布。研究后认为:花岗岩和变质岩均可作为金矿的矿源岩石。铅同位素的线性展布不能用铅演化的二阶段模型加以解释,而应作为混合线来说明。     

福建平和钟腾铜矿床成岩成矿时代研究

钟腾铜矿床为位于华夏板块东南缘上杭—云霄构造-岩浆成矿带上的岩浆热液型矿床。岩石地球化学分析表明矿区3种主要花岗质岩石均属于高钾钙碱性系列岩石,具有高钾、富碱、贫硅、低钛的特征,部分岩石有过铝质的特点,轻稀土元素富集,具有弱负铕异常。微量元素以富集大离子K、Rb、Th等亲石元素,亏损Nb、Ta、Ti等高场强元素为特征。LA-ICP-MS锆石U-Pb测年获得矿区3种岩石年龄分别为(103.5±0.4) Ma、(102.2±0.4) Ma、(103±0.4) Ma,锆石ε_Hf(t)值在-2.9~2.0,两阶段模式年龄(T_DM2)为1.04~1.35 Ga。矿石辉钼矿的Re-Os同位素测年获得等时线年龄为(105±2.5) Ma,说明成矿主要与燕山晚期花岗岩侵入有关。综合本次研究及相关区域资料,认为钟腾铜矿区的花岗岩为I型花岗岩,花岗岩及相关矿床形成于东南沿海地区110~90 Ma期间的古太平洋板块向西俯冲的大陆边缘背景。     

Geochemical features of rare-metal granites of the Zashikhinsky Massif,East Sayan

The paper presents detailed geochemical data on the rocks of the Zashikhinsky Massif and mineralogical–geochemical characteristics of the ores of the eponymous deposit. The rare-metal granites are divided into three facies varieties on the basis of the degree of differentiation and ore potential: early facies represented by microcline–albite granites with arfvedsonite, middle facies represented by leucocratic albite–microcline granites, and late (most ore-bearing) facies represented by quartz–albite granites grading into albitites. Microprobe data were obtained on major minerals accumulating trace elements in the rocks and ores. All facies of the rare-metal granites, including the rocks of the fluorite–rare-metal vein, define single compositional trends in the plots of paired correlations of rock-forming and trace elements. In addition, they also show similar REE patterns and spidergrams. The latter, however, differ in the depth of anomalies of some elements. Obtained geological, petrographic, and geochemical data suggest a magmatic genesis of the rocks of different composition and their derivation from a single magma during its differentiation. On the basis of all characteristics, the Zashikhinskoe deposit is estimated as one of the largest tantalum rare-metal deposits of alkaline-granite type in Russia.     

Granitoid magmatism of the Japan and Okhotsk seas

This paper presents a study of Middle Paleozoic, Late Paleozoic, Early Cretaceous, and Early—Late Cretaceous granitoid complexes from two Pacific marginal seas. The granitoid complexes are subdivided into two large groups: (1) mantle-crust derivatives, including andesite differentiates, and (2) crustal palingenetic granites. In terms of formation depth, they are subdivided into abyssal, mesoabyssal, and hypabyssal granites, with decreasing depth from the old to young complexes. It was established that the granitoids of different genesis have peculiar geochemical features. The granitoids of distinguished genetic types differ in the content and proportions of alkalis, primarily, K, as well as Rb, Sr, and Ba. The palingenetic granites show the predominance of K over Na and are classified as high-K calc-alkaline rocks, whereas andesitic derivatives correspond to the calc-alkaline rocks. The former are characterized by the higher Rb and Ba contents, which is related to the geochemical affinity of these elements to K. In contrast, the Okhotsk Sea rocks are characterized by the predominance of Na over K, the elevated Sr content, and the lower Ba and Rb contents. In terms of geodynamic setting, the studied granitoids fall in the field of volcanic arcs and syncollisional rocks. The latters are represented by the palingenetic granitoids of the Sea of Japan.     

蓬莱9-1潜山岩性组成及其对储层发育的控制

PL9-1潜山油藏是渤海湾盆地储量最大的古潜山油气藏之一,探明储量过亿吨.该油藏发育于庙西北凸起鞍部的中生界花岗岩侵入体顶部.凸起端部变质岩中没有油气发现.油气的分布受岩性控制明显.综合岩心观察、薄片鉴定、X粉晶衍射以及常量元素分析等技术手段,通过对比不同岩石类型的矿物组成、储集空间类型及发育程度,探讨了岩性组成对储层发育的控制作用.研究表明,变质岩中裂缝和孔隙均不发育,不能形成有效储层.花岗岩主要储集空间类型为孔隙-裂缝型,总体具有从砂质风化带→砾质风化带→裂缝带→基岩带,储集空间组合类型从孔隙→孔隙+裂缝→裂缝→不太发育的微裂缝的变化特征.储层厚度大,成层性强,可形成有效的规模性储层.花岗岩与变质岩的矿物组成差异控制了研究区优质储层的发育.变质岩中长石含量极低,不能形成溶蚀孔隙,较高含量(30%~50%)的片状矿物使其在应力作用下易发生塑性变形,不易产生裂缝.花岗岩具有很高的长石含量和含量很低的片状矿物,不仅容易被风化并产生溶蚀孔隙,而且易于发生脆性变形形成裂缝.      

青藏高原内部三条磨拉石带的确定及其构造意义

造山带地球化学研究的目标主要是为重建古板块构造格局服务,其次是探讨古造山带不同演化阶段岩石的形成、演化、变质及其所反映的大陆动力学和深部地幔过程。造山带演化分为5个阶段,各个阶段的火成岩具有不同的特征,地球化学研究的任务就是要识别出各个阶段岩石产物的特征、来源、成因和形成环境。文中着重讨论了造山带火成岩的若干地球化学问题。笔者指出：蛇绿岩主要分为岛弧拉斑玄武岩（IAT）和MORB两种,最近的研究发现,蛇绿岩中有来自富集地幔的信息。岛弧火山岩突出的地球化学特征是富集大离子亲石元素、ω（Th）＞ω（Ta）和Nb,Ta亏损,这是由于消减带物质加入的结果,本质上是一个（深源）陆壳混染的问题。花岗岩可能是幔源与壳源之间混合的连续谱系,花岗岩成因类型的控制因素主要是不同类型的源岩而不是构造环境。双峰式火山岩的成因比原先想象的要复杂,可以产于各种构造环境。文中还讨论了造山带地球化学研究方法的问题。     

花岗质次火山岩的成因类型及成矿专属性

与花岗质火山岩具不同的成因类型相似,自然界也存在着不同成因类型的次火山岩。后者与三大成因类型花岗岩相对应,亦可分为壳型次火山岩,过渡型次火山岩和幔型次火山岩三类。亮型次火山岩主要与U、REE,W、Sn、Nb、Ta等矿产有关系,属花岗岩矿床系列。过渡型次火山岩主要与Cu、Pb、Zn、Ag、Au有关,并伴有W、Sn成矿、属斑岩矿床系列。幔型次火山岩主要与黄铁矿型Cu、Pb、Zn多金属矿化有关,属海相火山岩矿床系列。     

滇西地区中酸性侵入岩的平均化学成分

滇西地区以花岗岩类为主的多旋迴中酸性侵入岩十分发育而著称。它们的化学成分是研究区域岩浆演化规律的基础资料,对阐明区内中酸性侵入岩的基本特点,区域地球化学特征,造岩元素的区域浓度克拉克值,探索区域地质构造环境并指导普查找矿均具有一定意义。     

诸广山中生代花岗岩演化序列初步研究

以往曾经认为诸广山岩体主要形成于加里东期后来根据同位素年龄数据确认主要由燕山期花岗岩组成。近年来,北京铀矿地质研究所戎嘉树等(1977)及中南二三○研究所刘立均等(1980)所做的工作表明,在过去所称的燕山早期花岗岩中有相当一部份应划归印支期,即三叠纪。在诸广山岩基中,早古生代花岗岩除一些出露