衡山地洼花岗岩的断裂重熔成因

衡山复式花岗岩由南岳岩体和白石峰岩体组成,形成于西缘大断裂的剪切阶段,并与韧性变形变质岩、断裂混合岩构成了紧密共生的(两期)三位一体组合。研究表明,白石峰岩体是由早期眼球状混合岩高程度熔融而成的,南岳岩体则是高变质相韧性断层岩重熔的产物,二者均属断裂重熔。重熔过程是一种流体开放体系,重熔作用沿断裂呈线带状发生,与深部高温热流体沿断裂带的注入、聚集有关。断裂重熔是地洼花岗岩的形成方式之一,其实质是地洼块断(造山作用)重熔。     

信宜东镇片麻状花岗质岩石同位素年龄的地质意义

信宜东镇的片麻状花岗质岩石是一种糜棱岩化混合岩一混合花岗岩；由岩体边部至中心，具有由长石化区域变质岩→条纹（条痕，斑点）状混合岩→眼球状混合岩→粗粒黑云混合花岗岩（具塑性流动特点）的分带规律，岩石内常含有早期的经受过韧性变形的长石，云母和石英等残留矿物（古成体）它是花岗质原岩经过深层次韧性剪切与重熔形成的原地型混合岩－混合花岗岩，再经受中浅层次脆韧性变形（糜棱岩化）形成的，其中锆石Ｐｂ－Ｐｂ法最古     

衡山变质核杂岩体西缘剥离断层及其对铀成矿的控制作用

衡山变质核杂岩体是由元古界深变质岩和燕山期复式花岗岩体组成，其西缘的界版剥离断层是区域深断裂的一部分，在断裂下盘山现糜棱岩－混合岩带具韧性变形特征，沿断裂已发现一些有意义的铀矿化，根据剥离断层控矿模式，提出在断裂上盘王冲－谢马冲地段寻找陡倾正断层与离断层交切处的隐伏铀矿的设想。     

混合岩的基本特征及其在岩理学上的存在

用Ｐ－Ｔ图解说明岩石从低温到高温必经的４个阶段：未变质的岩石→变质岩（狭义）→重熔型混合岩→岩浆岩，从而指出重熔型混合岩化作用阶段是不可逾越的。从图２中的Ｎ线→Ｇｒ域→Ｃ″（或Ｃ＇）线的高温一侧，岩石从脱水反应→去硅脱碱作用→全部重熔，岩汁和交代型混合岩化作用必将产生。     

混合岩的基本特征及其在岩理学上的存在

用Ｐ－Ｔ图解说明岩石从低温到高温必经的４个阶段：未变质的岩石→变质岩（狭义）→重熔型混合岩→岩浆岩，从而指出重熔型混合岩化作用阶段是不可逾越的。从图２中的Ｎ线→Ｃｒ域→Ｃ″（或Ｃ′）线的高温一侧，岩石从脱水反应→去硅脱碱作用→全部重熔，岩汁和交代型混合岩化作用必将产生。     

湖南连云山剪切重熔型花岗岩的野外构造岩相分带

湖南连云山扁透镜状花岗岩侵位于长寿街—双牌走滑断裂带内。野外地质剖面观测结果表明 ,该岩区存在如下连续过渡的构造岩相分带 :未卷入断裂变形变质的冷家溪群 (围岩 )→含石榴子石云母石英构造片岩→混合岩化石英云母片岩→条带状、肠状混合岩夹透镜状花岗质小块岩→片麻状、块状黑云二长花岗岩 (主体 )。区域地质构造解析结果表明 ,连云山花岗岩与晚三叠世—侏罗纪 NNE向会聚走滑断层动热变质—剪切重熔型岩浆作用有关。     

封面故事

湖南衡山岩体西缘界牌拆离断裂带的野外变形特征和韧性剪切作用显微组构特征。通过深入研究衡山变质核杂岩西侧拆离断层的结构和运动学特征,确认拆离断裂带经历了从深部韧性变形向浅部脆     

哈尔里克山晚古生代混合岩地质特征、年代学及其构造意义

哈尔里克山位于天山造山带东北缘,是古亚洲洋板片俯冲、弧—陆（或弧—弧）增生拼贴造山作用的产物。出露于哈尔里克山南麓的中—高级变质带中发育有混合岩,其成因和时代尚无详细研究。文章对哈尔里克变质带中的混合岩进行了野外岩相—构造分析与LA-ICP-MS 锆石U-Pb 年代学研究。结果显示,该混合岩与高级变质沉积岩紧密伴生,可能是变质沉积岩经部分熔融作用形成的。混合岩带中多条变形程度不同的浅色岩脉的锆石U-Pb 年龄均在332~330 Ma 之间,部分浅色岩脉具有典型的同构造变形特征,从而可以限定哈尔里克山南麓变质带的混合岩化作用发生在330 Ma 左右。结合前人对研究区变质岩和侵入岩的研究结果以及区域地质演化特征,笔者认为哈尔里克山地区在330 Ma 可能已进入了后造山伸展阶段,该变质带中混合岩可能形成于后造山伸展减压部分熔融,是哈尔里克岛弧基底的组成部分,其折返抬升与同期后造山岩体的侵位作用有关。     

金川超基性岩体可分解为“南岩带”与“北岩带”

金川超基性岩体可分解为"南岩带"与"北岩带"."南岩带"由Ⅱ、Ⅳ号小岩体组成,"北岩带"由Ⅰ、Ⅲ号小岩体组成,南、北岩带分别位于大理岩构造透镜体的南、北两侧.在超基性岩体侵位前,古元古代地层产生了高角闪岩相峰值变质变形,顺大理岩层发育逆冲推覆型韧性剪切滑动系统,形成了变质带倒置的层状变质岩片、构造混合岩、剪切流变褶皱及...     

新资深大断裂变质带特征、成因及活动演化

在前人研究成果和野外调查基础上,对新资深大断裂变质带特征进行系统总结,从宏观构造、显微构造与组构、岩石矿物学、年代学和地球化学等多学科角度综合研究,分析了新资断裂带各类岩石组构成因,并建立了其活动演化期次。新资深大断裂变质带构造岩主要包括定向组构系列岩石和块状系列岩石,主要是由早期的韧性变形变质作用阶段和晚期的脆性破碎作用阶段先后作用形成。越城岭岩体西侧规模巨大的花岗片麻岩带应属新资深大断裂变质带的一部分,属早期活动的产物,其原岩为越城岭岩体,为断裂变质和动力热流变质作用形成。韧性剪切系列岩石按变形变质强度可分为高温高压韧性剪切带和中温高压韧性剪切带,表明韧性剪切作用具有多期性。新资断裂带活动演化主要经历了四个阶段,始于加里东期,至喜山期均有活动,现在的新资断裂带是经过多个阶段不同类型变质作用由东向西不断迁移和相互叠加的结果。     

Contrasting magmas in metapelitic and metapsammitic migmatites in the Cooma Complex, Australia

Metapelite-derived migmatites (“bedded migmatites”) formed in the low-pressure/high-temperature (LPHT) Cooma Complex, southeastern Australia, contain magma (neosome and leucosome) confined to the metapelitic beds in which they were generated. The metapsammitic beds were more ductile than the metapelitic beds (and the metapelitic parts of graded beds), which underwent fracture and boudinage, thereby providing space for the magma, though some also occurs in axial surface folia. Transitions from bedded to stromatic migmatites can be seen, but the magma mainly remained in the metapelites, even in the most strongly deformed stromatic migmatites. This, together with boudinage and transposition of the leucosome, as well as microstructural evidence of quartz recrystallization, suggest that much or most of the stromatic layering was formed by solid-state deformation. In contrast, magmas (neosomes) formed by partial melting of feldspathic metapsammites at Cooma moved out of their parent rocks, and coalesced into veins and small intrusions of diatexite, because (1) the host rocks deformed more homogeneously, and no interboudin space was made for the melts, and (2) the melt escape threshold was exceeded, probably with the assistance of deformation. Metapsammite melting occurred after solidification of the metapelite-derived magma, and the mobile metapsammite-derived magma (diatexite) disrupted and incorporated fragments of the metapelitic migmatites. The metapsammite-derived magma, together with this solid metapelitic material, locally coalesced into bodies closely resembling the Cooma Granodiorite.     

陇县904地区混合岩型铀矿成矿特征的讨论

含铀混合岩大部分位于古陆隆起带边部、ＮＷ向花岗岩外接触带。深大断裂系统在成矿成岩中占有相当重要的地位。燕山期构造和岩浆活化，对原有的构造和矿化进行了强烈改造。在混合岩中发现了两种主要成矿类型，即铀一赤铁矿型和铀一碳酸盐型。     

辽宁小盘岭金矿床混合岩特征及与金成矿的关系

辽宁绥中小盘岭金矿床位于混合岩化中心带的混合花岗岩内，其中间带主要为混合片麻岩，外带为以条带状混合岩为主的混合杂岩。通过对各类混合岩中造岩矿物光学特征的对比，发现随着混合岩化程度的增强，矿物光学特征有规律地变化。根据岩石中矿物的交代关系，确定在混合岩化作用过程中至少有4期热液活动。通过将区域原变质岩、混合岩和与金矿成矿有关的花岗岩类岩石地球化学成分的对比，中心带的混合花岗岩与金成矿关系密切，其原岩——厚层状黑云母斜长片麻岩很可能是金成矿的重要矿源岩，其中发育的长英质岩脉是金成矿的一个重要标志。     

云开隆起区热中心式区域混合岩的成因研究

云开隆起区不同混合岩化程度的混合岩在空间多以黑云母花岗岩为中心，呈环带状分布，混合岩的矿物空间分布研究表明，亲成体矿物具有随机分布特点，说明为熔浆结晶成因，结晶温度在５６０－５８０℃，条带状混凳夺的质量平衡研究表明，新成体和古成体的成分具有很好的相关性，递进熔融作用合理解释了这种混合岩的成因及其空间分布规律。     

辽吉东部层状混合岩的成因

辽吉东部的层状混合岩与上、下围岩始终保持整合接触,反映它的体系基本上是封闭的,没有外来组份的加入。其组构、岩石化学、微量元素和稀土资料等表明层状混合岩不足岩浆型的,而是重熔岩浆型的,其原岩是沉积变质岩。     

On the Origin of Migmatites in Yunlu, Western Guangdong

Partially migmatized rocks, banded migmatites, augen-banded migmatites and gneissic migmatites are developed successively from Xindong to Yunlu, Gaozhou, Guangdong Province in the Yunkai Caledonian orogenic belt at the border between Guangdong and Guangxi. Mass-balance calculations, statistical analysis of the textural relations and mineralogical and geochemical studies of the migmatites and the study of the metamorphlc setting of the Yunlu area indicate that the migmatites in the study area were primarily formed by anatexis without remarkable introduction of foreign components such as K, Na and Si and removal of Ca, Fe, Mg, etc.     

五马箐组变质杂岩岩石化学特征及地质意义

米易海塔地区五马箐组地层,前人争议较多。争论焦点主要围绕其时代归属及成因问题。通过野外实际工作,发现五马箐组片岩、片麻岩内有大量长英质脉体。据其空间展布、岩石学及稀土元素特征,判定具混合岩特征。因此认为五马箐组地层岩石组合与河口群地层存在一些可比性,时代早于会理群,晚于康定群,属区域动热变质作用及混合岩化作用形成。     

Effect of metamorphism and partial melting of host rocks on zircons

Abstract Zircons have been studied from different layers of migmatites (from Arvika, western Sweden and Nelaug, southern Norway) and from a paragneiss (from Arvika) associated with one of the migmatites. The main purpose of the investigation is to establish whether or not information about zircons can help in the elucidation of the parentage and rock-forming processes of migmatites.
The elongation ratio of zircons from all layers is small and characteristic of sedimentary zircons. Further, the absence of characteristic colours and the growth trends of the zircons (indicated by the reduced major axes) observed in the various samples both support a sedimentary parentage for these rocks. The zircons of all layers exhibit secondary growth (overgrowth, outgrowth and multiple growth) due to metamorphism. Compared with the zircons from the paragneiss, those of the migmatite layers are more clouded and less rounded, some of them becoming opaque or even skeletal; this is especially true of the zircons from the leucosomes. These observations indicate an alteration of the original sedimentary zircons in the migmatite, especially in the leucosomes, in response to the migmatization process, previously interpreted as partial melting.     

Retrograde melt–residue interaction and the formation of near‐anhydrous leucosomes in migmatites

Considering physical segregation of melt from its residue, the chemical potentials of the components (oxides) are the same in both when segregation occurs. Then, as P–T conditions change, gradients in chemical potential are established between the melt‐rich domains and residue permitting diffusional interaction to occur. In particular, on cooling, the chemical potential of H₂O becomes higher in the melt segregation than in the residue, particularly when biotite becomes stable in the residue assemblage. Diffusion of water from the melt to the residue promotes crystallization of anhydrous products from the melt and hydrous products in the residue. This diffusive process, when coupled with melt loss from the rocks subsequent to some degree of crystallization, can result in a significant degree of anhydrous leucosome being preserved in a migmatite with only minor retrogression of the residue. If H₂O can diffuse between the melt segregation and all of the residue, then no apparent selvedge between the two will be observed. Alternatively, if H₂O can diffuse between the melt segregation and only part of the residue, then a distinct selvedge may be produced. Diffusion of H₂O into the residue may be in part responsible for the commonly anhydrous nature of leucosomes, especially in granulite facies migmatites. Diffusion of other relatively mobile species such as Na₂O and K₂O has a lesser effect on overall melt crystallization but can change the proportion of quartz, plagioclase and K‐feldspar in the resultant leucosome. The diffusion of H₂O out of the melt results in the enhanced crystallization of the melt in the segregation and increases the amount of resulting anhydrous leucosome relative to the amount produced if melt crystallized in chemical isolation from the residue. For high residue:melt ratios, the proportion of resulting near‐anhydrous leucosome can approach that of the proportion of melt present at the onset of cooling with only minor loss of melt from a given segregation required. Crystallization of melt segregations via the diffusion of H₂O out of them into the host may also play a major role in driving melt‐rich segregations across key rheological transitions that would allow the expulsion of remaining melt from the system.     

高级变质岩中深熔作用的相平衡研究

深熔作用在高级变质岩中非常普遍并受到广泛关注。自20世纪90年代以来,随着变质相平衡研究的突破性发展,利用THERMOCALC程序和视剖面图方法可以定量研究固相线以上的熔体形成、熔体分馏和退变质反应。变质沉积岩中的熔融作用主要有三种机制饱和水固相线上的熔融、白云母脱水熔融和黑云母脱水熔融。在模拟泥质岩石的KFMASH体系和NCKFMASH体系中的相平衡计算表明,NCKFMASH体系中铁镁矿物的相平衡关系受KFMASH亚体系中矿物相平衡关系的控制,但KFMASH亚体系中固相线位置要比实际的高50~60℃。因此,模拟泥质岩石的固相线以上的相平衡关系最好在NCKFMASH或组分更多的体系中进行。相平衡研究表明麻粒岩相岩石的保存与熔体丢失有关;混合岩的形成过程包括部分熔融作用、不同程度熔体分凝与汲取和不同程度的逆反应和退变反应。