辽北新宾?苇子峪地区太古宙花岗质岩石的形成年代、成因及其地质意义

辽北新宾?苇子峪地区的花岗质岩石主要由英云闪长质?奥长花岗质片麻岩和二长花岗岩?正长花岗岩岩体等组成。为确定其形成年代及成因, 对这些花岗质岩石进行锆石U-Pb-Hf同位素和全岩地球化学分析。锆石LA-ICP-MS U-Pb同位素定年结果表明这些花岗质岩石均形成于新太古代, 英云闪长质和奥长花岗质片麻岩的岩浆结晶年龄分别为2588±4 Ma (MSWD=1.3)和2587±6 Ma (MSWD=1.8), 二长花岗岩?正长花岗岩则侵位于2555±4 Ma (MSWD=0.51)。全岩地球化学和锆石Lu-Hf同位素研究表明, 英云闪长质?奥长花岗质片麻岩形成于俯冲板片的部分熔融, 其原始岩浆在上升过程中受到地幔楔岩石的交代; 而二长花岗岩?正长花岗岩中一部分岩浆起源于变质杂砂岩的部分熔融, 其余形成于以变质玄武岩与变质沉积岩为主要成分的混合源区的部分熔融。结合近年的研究成果, 认为新宾?苇子峪地区的新太古代花岗质岩石可能形成于活动大陆边缘的动力学背景。     

新丰花岗岩稀土分布型式的初步研究

新丰花岗岩中有两类稀土分布型式,在中心相花岗岩中轻重稀土比值较大(LREE/HREE>3),有着不显著的铕负异常(δEu>0.5);而在过渡相花岗岩中轻重稀土比值较小(LREE/HREE<8),有着较显著的铕负异常(δEu<0.5)。在岩体中轻重稀土比值和δEu值有随着SiO_2含量增加而减小的变化规律。经研究,中心相花岗岩中稀土分布型式主要与褐帘石和斜长石有关,而过渡相花岗岩主要与独居石、磷钇矿、斜长石和褐钇铌矿有关。许多证据表明新丰花岗岩应属岩浆型花岗岩,而且是由中心相花岗岩往过渡相花岗岩演化的。花岗岩中和矿物中稀土元素分布型式的变化规律也正反映了这样的演化过程。     

国家自然科学基金研究专著《中国东南部晚中生代花岗质火山-侵入杂岩成因与地壳演化》

本书从壳幔作用角度剖析了中国东南部晚中生代花岗岩的形成过程，总结了三类花岗质火山-侵入杂岩的时空分布规律及其与伸展构造的关系．从玄武质角砾岩筒中的辉长质麻粒岩包体，获取了玄武岩浆底侵作用的直接证据．在综合研究的基础上，建立了东南沿海晚中生代构造岩浆作用模式．论述了内陆S型花岗岩形成与演化的规律．     

咸沟岩体地质地球化学特征及成岩机制探讨

咸沟岩体位于华北地台北缘西段．主岩体为二云母花岗岩，成岩时代为３９９．８±１．８２．１Ｍａ，内有岩浆演化晚期的白云母花岗岩侵入，与主岩体有迥然不同的地球化学特点．前者显示出不同地壳物质混合的岩浆特征，后者属典型的Ｓ型花岗岩．结合区域构造演化分析，认为咸沟岩体形成于拉张环境，源岩可能为下地壳的英云闪长岩．下地壳的深熔岩浆在上升迁移过程中，遭受了富含泥质的陆壳物质的强烈混染，混染岩浆向Ｓ型岩浆方向演化．     

四川康定县大雪山超单元地球化学特征

根据花岗岩同源岩浆演化序列,将康定县大雪山超单元花岗岩体划分为3个单元,岩石组合特征为石英闪长岩、花岗闪长岩、二长花岗岩,具有明显的成分-结构演化特征。同位素年龄为104~121 Ma,时代属燕山晚期的Ⅰ型花岗岩。通过对岩石化学、稀土元素、微量元素等数据的分析,论述了折多山岩体的物质来源、构造环境及其成因。     

西秦岭美武花岗岩地球化学特征

美武花岗岩在揭示西秦岭地区中生界构造演化方面具有特殊的作用。本文通过岩石化学和微量元素地球化学特征研究,对美武花岗岩岩体演化过程中的地球化学特征变化、岩体戍因及其形成的构造演化背景进行了探讨。结果表明,该岩体随着侵入期次由早向晚演化,岩石化学和地球化学特征具有明显的变化规律,反映出美武复式岩体各单元为同源岩浆系列结晶而成。它们之间既有差异性,又具有继承性。美武花岗岩形成于地壳的部分熔融,其岩浆源岩主要为高钾角闪质类岩石。而岩浆混合作用也造成沉积性质物源的加入,同时造成不同侵入单元体之间地球化学性状差别。     

山西芦芽山早元古代紫苏花岗岩的成因：地球化学和Nd同位素证据

芦芽山紫苏花岗岩体主要由紫苏二长岩、紫苏石英二长岩、紫苏花岗岩和钾长花岗岩组成.这些花岗质岩石表现TiO2,P2O5,K2 O,Zr,Nb,Y,Pb,La,Ce和Ba富集以及高的K2O/Na2O比值,而MgO,CaO,Mg#,Th,U亏损和低的Sr/Ba、Rb/Ba比值.Zr,Nb和Ce与SiO2反相关,这与Ⅰ型花岗岩恰恰相反.这些岩石的Sm-Nd同位素特征比较均一,初始εNd值为-5.93到-6.97,亏损地幔模式年龄为2.67到2.78 Ga.这些特征说明紫苏花岗质岩浆起源于晚太古代下地壳的部分熔融,即铁镁质麻粒岩在富CO2流体存在和异常高温下的部分熔融,石榴石作为主要残余相.它们经历了干燥高温岩浆的结晶分异,辉石、斜长石、磷灰石和钛铁矿可能为早期结晶相.芦芽山紫苏花岗岩的岩浆作用形成于东部陆块和西部陆块(～1850 Ma)主碰撞期后的俯冲洋壳拆沉、地幔上隆导致的热松弛构造背景.     

西秦岭光头山花岗岩锆石U-Pb年代学及其地质意义

光头山花岗岩体出露于勉略缝合带北侧, 主要由英云闪长岩和二长花岗岩组成。英云闪长岩表现为片麻状构造, 局部英云闪长岩糜棱岩化形成花岗质糜棱岩。而二长花岗岩在糜棱岩带形成之后侵位, 含有少量的石榴石,弱的片麻状到块状构造。LA-ICPMS 锆石原位U-Pb同位素定年结果表明, 光头山岩体为两个阶段侵位, 糜棱岩化英云闪长岩( 样品GT18-01)的侵位结晶年龄是221±6Ma, 而二长花岗岩(样品GT11-01)的结晶年龄是199±4Ma,代表了晚期二长花岗岩形成的时代。结合区域构造背景和前人研究的地球化学特征, 早期的英云闪长岩可能在勉略洋盆闭合前的岛弧发育阶段侵位, 代表了洋壳俯冲的弧岩浆活动的产物。然后扬子地台与秦岭微陆块拼合, 形成勉略缝合带。约199Ma秦岭主造山期同碰撞岩浆活动形成了晚期(石榴石)二长花岗岩。因此, 勉略洋盆闭合和勉略缝合带形成时期大约为221～199Ma 。     

中国东南部加里东期花岗岩的特征和成因

中国东南部地槽褶皱区伴随加里东早期和晚期运动,有花岗老化和岩浆侵入活动。早期形成混合花岗岩和片麻状花岗岩;晚期形成块状花岗岩。前者具最大微斜长石——更、中长石组合;后者为正长石——正长微斜长石——更、中长石组合类型。经研究表明,两期花岗岩具有 Na_2O、CaO 低,富 Al_2O_3、K_2O 的岩石化学特性,它们属铝过饱和花岗岩,微量元素贫 V、Cr、Ni、Co、Cu、Pb、Zn,而富W、Sn、Be、U、Ga 等,付矿物以含钛矿物种类和数量较多,出现饰族稀土元素付矿物而缺亿族稀土元素矿物为特征。上述特征的一致性,表明两期花岗岩具有相同的物质来源。从黑云母富铁,为铁质黑云母,在 Fe~(3+)—Fe~(2+)—Mg 图上落在Ni—Nio 缓冲线之下,说明加里东花岗岩是在氧逸度低的还原环境下形成。稀土元素分配模式,两期岩体也很相似,出现铕的亏损,它明显地不同于华南慢源型的稀土模式。因此加里东花岗岩由地壳沉积物改造而成,属改造型花岗岩成因系列。两期花岗岩虽有相同的物质来源.但有不同的成因方式;地楷沉积物在角闪岩相变质基础上发生部分重熔,低熔组分交代围岩形成加里东早期武功山型混合花岗岩;进一步发展形成深层流化花岗岩——慈竹型和侵入混合花岗岩——石科型。当深部沉积物重熔形成岩浆,它侵位到较上层位形成早期片麻状花岗岩和晚期块状花岗岩。     

岩浆底侵作用研究进展

介绍了近年来国内外在岩浆底侵作用研究方面的部分工作成果,重点论述了岩浆底侵作用与花岗岩成因、岩浆底侵作用与地壳增生、岩浆底侵作用与盆地演化以及岩浆底侵作用与区域成矿等方面的主要进展.     

阿尔泰诺尔特地区花岗岩岩浆的分凝作用

诺尔特地区位于阿尔泰北部山区 ,西伯利亚板块西南缘。花岗岩广泛分布 ,主要为加里东晚期、华力西中晚期及燕山期花岗岩。文章选取诺尔特地区各时期代表性岩体进行岩浆分凝作用的研究 ,确定的动力学参数包括岩浆的含水量、粘度及密度。分凝速度的计算表明 ,区内各岩体花岗质岩浆中分凝作用是存在的 ,但是分凝速度较小 ,分凝作用对于大颗粒的残余体的分离作用是明显的 ,而对于小颗粒的残余体的分离作用很小。经过分凝作用之后 ,岩浆的成分发生了变化 ,岩浆中依然存在小颗粒的耐熔残晶     

Hf isotope composition of zircons and implication for the petrogenesis of Yajiangqiao granite,Hunan Province,China

In the peralumineous granite of Yajiangqiao zircon population can be divided into two groups (i.e. Zircon Ⅰ and Zircon Ⅱ), which were formed in magmatic chamber and in emplacement place, respectively. The Hf isotope compositions of two stages of zircon show that the host magma was essentially derived from crustal material by melting. However, some higher 176Hf/177Hf ratios indicate that the granitic zircons should contain fine crystal of zircon formed in mantle-derived magma. In fact, the backscattered electron imaging and the electron microprobe analysis reveal that there is another type of zircon included within Zircon Ⅰ, which is quite different from Zircon Ⅰ and Zircon Ⅱ in morphology and chemistry. They are considered to be the product of the mantle-derived magma intruded into the granitic magma chamber at the beginning of anatexis. Thus,it is suggested that the formation of Yajiangqiao granite is related to the underplating of mantle magma.     

内蒙古中部乌拉山-大青山地区富铝片麻岩年代学特征

内蒙古中部乌拉山岩群是一套变质程度为高角闪岩相-麻粒岩相的早前寒武纪高级变质岩系,出露于内蒙古中部。为划分乌拉山-大青山地区富铝片麻岩的原岩形成时代,通过对侵入乌拉山岩群黑云石榴斜长片麻岩的石英闪长质片麻岩和紫苏花岗质片麻岩变质深成体进行年代学研究,本次研究涉及的实验样品共6件,分别于内蒙古中部乌拉山-大青山地区片麻岩中和变质深成岩中各取3件。分别为矽线石榴黑云斜长片麻岩(TWB19)、黑云斜长片麻岩(TWB20)、含橄榄石方解石大理岩(TWB18)和紫苏花岗质片麻岩(TW7)、石英闪长质片麻岩(TWB6)和花岗闪长质片麻岩(D1227)。结果表明：紫苏花岗质片麻岩(TW7)的加权平均年龄为2462±13Ma,花岗闪长质片麻岩(D1227)加权平均年龄为2512±24Ma,由于后期构造事件对岩石的改造,锆石的实际年龄应更大一些。可见,乌拉山富铝片麻岩原岩形成年代早于2.5Ga。石英闪长质片麻岩(TWB6)的变质年龄为2.2Ga和1.9Ga,指示乌拉山-大青山地区遭受古元古代早期和晚期构造热事件叠加改造。综上所述,乌拉山-大青山地区富铝片麻岩最晚形成时代限定在2.5Ga。     

北山中部地区闪长岩-花岗岩类成因及构造背景

北山中部地区中酸性侵入岩以海西中晚期为主，加里东晚期次之。岩石类型有辉长岩、闪长岩、花岗闪长岩、斜长花岗岩和花岗岩类。岩浆活动分为3个旋回6期，其中海西中期第2，3期和海西晚期岩浆活动员为强烈。研究区岩体多呈岩株、岩枝和岩基产出，围岩普遍发育混合岩化和同化混染，岩石具花岗结构，块状-(巨)斑状构造。岩石化学成分为钙碱性系列，闪长岩分异程度低，斜长花岗岩和花岗闪长岩分异程度中等，花岗岩类相对较高。加里东晚期和海西晚期花岗岩类属S(海西)型花岗岩类，海西中期闪长岩、花岗闪长岩和斜长花岗岩类则属I型(科迪勒拉)，闪长岩属交代(花岗岩化)成因，花岗闪长岩-花岗岩类属岩浆成因。加里东晚期花岗岩是中-晚志留世北山地区哈萨克斯坦板块向南俯冲使上地壳局部熔融的结果；海西中期闪长岩是混合岩化(花岗岩化)的产物；花岗闪长岩和斜长花岗岩是裂谷扩张阶段上地慢部分熔融的结果；而海西晚期花岗岩是裂谷萎缩和闭合阶段地壳局部熔融的结果。     

四川盐源西范坪斑岩铜矿的钾长环斑结构及其意义

四川盐源西范坪斑岩铜矿床中存在大量钾长环斑结构。研究表明这一结构是由正在冷凝的岩浆分泌出的成矿流体与刚结晶的斜长石相互作用形成的。在流体 -矿物相互作用过程中 ,流体从已经结晶的矿物尤其是黑云母中萃取出大量铜等成矿物质 ,从而进一步提高了体系的成矿能力。钾长环斑结构的出现不仅为矿床的岩浆热液成因提供了佐证 ,而且是一种良好的找矿标志。     

Oxygen isotope evidence for two-stage water-rock interactions of the Nianzishan A-type granite in NE China

The oxygen isotope ratios of whole-rock, common rock-forming minerals and zircon from Mesozoic A-type granitic pluton at Nianzishan in northeastern China were analyzed by the conventional BrF5 method and the laser-probe technique, respectively. Both whole-rock and rock-forming minerals show large δ18O variations up to 5.5%. with significant oxygen isotope disequilibrium between zircon and the other minerals, whereas the δ18O values of zircon are tightly clustered between 3.12%. and 4.19%. and thus lower than the normal-mantle δ18O values. These results indicate that the Nianzishan A-type granite experienced two-stage water-rock interactions subsequentially. The remarkably low zircon δ18O values are genetically due to sea-water exchange with granite protolith in the first stage, and the oxygen isotope disequilibrium fractionations between zircon and rock-forming minerals are caused by meteoric-hydro thermal alteration in the second stage. It is inferred that the 18O-depleted A-type granitic magma was derived from partial melting of subducted lower oceanic crust which was isotopically exchanged with seawater at high temperatures. In the process of granite emplacement into the upper crust, meteoric-hydrothermal circulation was triggered to overprint crystallizing granite under subsolidus conditions.     

Fluid mineralization of the Dajing Sn-polymetal deposit： Evidence from LA-ICP-MS analysis of individual fluid inclusions

LA-ICP-MS analyses on single fluid inclusions trapped in fluorite and quartz from the Sn-Cu orebody of the Dajing deposit and from the Sn ore-body of the Huanggangliang deposit were conducted to trace the source and evolution of Cu-rich and Sn-rich fluids in the Dajing deposit using the Rb/Sr and Sn/Cu ratios of the fluids. The results show that the Cu-rich fluids in the Dajing deposit, relatively rich in Na and probably derived from deep-seated basic magma, contain Cu several to several tens of times more than Sn, and Sr several to several tens of times more than Rb, while the Sn-rich fluids, relatively rich in K and probably derived from high level granitic magma, contain Sn several to several tens of times more than Cu, and Rb several to several tens of times more than Sr. It is suggested that the Sn-rich and the Cu-rich fluids were mixed at the stage of moderate to low temperature and low salinity, resulting in the formation of Cu-Sn orebodies at the central part of the Dajing deposit.     

塔里木盆地哈得逊油田成藏研究探讨

塔里木盆地哈得逊油田存在3个相互独立的油藏:石炭系东河砂岩油藏及中泥岩段薄砂层油藏、志留系柯坪塔格组上3亚段油藏。它们的油气来源于同一套烃源岩、具有相同的区域性盖层。多     

Petrogenesis of Paleoproterozoic Luyashan charnockitic rocks in Shanxi Province: Constraints from Geochemistry and Nd isotope

Luyashan charnockite pluton mainly consists of monzonite, adamellite, charnockite and syenogranite, which are characterized by the enrichment of TiO2, P2O5, K2O, Zr, Nb, Y, Pb, La, Ce, Ba and a higher K2O/Na2O and depletion of MgO, CaO, Mg#, Th, U and lower Sr/Ba and Rb/Ba. The negative correlations between Zr, Nb, Ce and SiO2 are distinct from I-type granites. Iso-topically Luyashan charnockite plutons are relatively uniform in Nd isotope, displaying initial εNd(t) (-5.93 to -6.97) and Nd depleted mantle model ages (2.67 Ga to 2.78Ga). These features indicate that Luyashan charnockitic magma derived from pre-existing late Archean crustal sources and the partial melting of mafic granulites probably under exceptionally high temperature with CO2-rich fluid. The garnet is a main residual phase during the partial melting. The original dry charnockitic magma experienced crystal fractionation of pyroxene, plagioclase, apatite and ilmenite during early crystallization. The geochemical evidence suggests that the Luyashan charnockitic magma was probably generated in the post-collision thermal relaxation and uplift tectonic setting after the main collision ( - 1850 Ma) between the Eastern and Western continental blocks.     

Phase equilibria of HP-UHP mica-schists in Jiangling,Eastern Dabieshan orogen

The HP-UHP metamorphic terrane of Jiangling, eastern Dabieshan comprises extensively distributed granitic gneisses, mica-schists and numerous eclogite blocks. The mica-schists generally contain garnet, phengitic muscovite, biotite, plagioclase, quartz, rutile and a small amount of epidote and hornblende. Study on petrography and phases equilibria in the NCKMnFMASH system indicates that the present mineral assemblages in mica-schists are not in equilibrium. The earlier stage of mineral assemblage represented by garnet and phengite reflects a HP-UHP condition. The garnet compositions and the phengite Si contents give a PT condition of 580-00 ℃ at 2.6-2.8 GPa. The garnet zonation records an earlier progressive metamorphic process which may be associated with the appearance of glaucophane, jadeite and lawsonite. The later stage of mineral assemblage characterized by the presence of biotite and plagioclase reflects a PT condition of 620-635℃ at 0.9-1.1 GPa, belonging to the HP amphibolite facies. The main mineral assemblage in mica-schists from the Jiangling region has recorded a complete HP-UHP metamorphic process.