川西甲基卡花岗伟晶岩型锂矿床中熔体、流体包裹体固相物质研究     

熊欣  李建康  王登红  刘丽君  代洪章 《岩石矿物学杂志》2019,38(2):241-253

川西甲基卡二云母花岗岩和伟晶岩内发育大量原生熔体包裹体和富晶体流体包裹体。为了查明甲基卡成矿熔体、流体性质与演化特征,运用激光拉曼光谱和扫描电镜鉴定了甲基卡花岗伟晶岩型锂矿床中二云母花岗岩及伟晶岩脉不同结构带内的原生熔体、流体包裹体的固相物质。分析结果表明,甲基卡二云母花岗岩石英内熔体包裹体的矿物组合为磷灰石+白云母、白云母+钠长石、白云母+石墨;伟晶岩绿柱石内富晶体流体包裹体的矿物组合主要为刚玉、富铝铁硅酸盐+刚玉+锂辉石、锂辉石+石英+锂绿泥石;伟晶岩锂辉石内富晶体流体包裹体的矿物组合主要为磷灰石、锡石、磁铁矿、石英+钠长石+锂绿泥石、萤石、富钙镁硅酸盐+富铁铝硅酸盐+富铁硅酸盐+石英;花岗岩浆熔体与伟晶岩浆熔体(流体)具有一定的差异,成矿熔体、流体成分总体呈现出碱质元素(Na、Si、Al)、挥发分(F、P、CO_2)含量增高及基性元素(Fe、Mg、Ca)降低的特征;包裹体中子矿物与主矿物的化学成分具有一定的差别,揭示出伟晶岩熔体(流体)存在局部岩浆分异作用,具不混溶性及非均匀性。因此认为,伟晶岩熔浆(流体)为岩浆分异与岩浆不混溶共同作用的产物,挥发分含量的增高(F、P、CO_2)使伟晶岩能够与稀有金属组成各类络合物或化合物,这对于稀有金属成矿起到了至关重要的作用。  相似文献   

Fluid Characteristics and Evolution of the Zhawulong Granitic Pegmatite Lithium Deposit in the Ganzi‐Songpan Region,Southwestern China     

XIONG Xin  LI Jiankang  WANG Denghong  LI Shanping  LIN Hao 《《地质学报》英文版》2019,93(4):943-954

The Zhawulong granitic pegmatite lithium deposit is located in the Ganzi-Songpan orogenic belt. Fluid inclusions in spodumene and coexisting quartz were studied to understand the cooling path and evolution of fluid within albite–spodumene pegmatite. There are three distinguishable types of fluid inclusions: crystal-rich, CO2–NaCl–H2O, and NaCl–H2O. At more than 500°C and 350~480 MPa, crystal-rich fluid inclusions were captured during the pegmatitic magma-hydrothermal transition stage, characterized by a dense hydrous alkali borosilicate fluid with a carbonate component. Between 412°C and 278°C, CO2–NaCl–H2Ofluid inclusions developed in spodumene (I) and quartz (II) with a low salinity (3.3–11.9 wt%NaCl equivalent) and a high volatile content, which represent the boundary between the transition stage and the hydrothermal stage. The subsequentNaCl–H2Ofluid inclusions from the hydrothermal stage, between 189°C and 302°C, have a low salinity (1.1–13.9 wt%NaCl equivalent). The various types of fluid inclusions reveal the P–T conditions of pegmatite formation, which marks the transition process from magmatic to hydrothermal. The ore-forming fluids from the Zhawulong deposit have many of the same characteristics as those from the Jiajika lithium deposit. The ore-forming fluid provided not only materials for crystallization of rare metal minerals, such as spodumene and beryl, but also the ideal conditions forthe growth of ore minerals. Therefore, this area has favorable conditions for lithium enrichment and excellent prospecting potential.  相似文献   

湖南仁里超大型稀有金属矿床的成矿特征与成矿模型   总被引：2，自引：0，他引：2  

周芳春  刘翔  李建康  黄志飚  肖国强  李鹏  周厚祥  石威科  谭黎明  苏俊男  陈虎  汪宣民 《大地构造与成矿学》2019,43(1):77-91

湖南仁里铌钽矿床位于燕山期幕阜山复式岩体西南缘,是我国近年来新发现的超大型花岗伟晶岩型铌钽矿床,伟晶岩脉产在花岗岩内部裂隙或灌入冷家溪群片岩中。矿区伟晶岩可分为微斜长石型、微斜长石钠长石型、钠长石型和钠长石锂辉石型四个类型分带,且脉体呈NE-SW向分布。相对于北东部的伟晶岩,南西部的伟晶岩具有较高的分异度,铌钽矿化程度高,仁里矿区为幕阜山地区铌钽矿化浓集中心,是幕阜山地区铌钽等稀有金属主要产地。较大规模伟晶岩脉具有较完善的分带,铌钽矿化主要产在伟晶岩内部的中-粗粒白云母钠长石带和锂云母石英带。各伟晶岩脉总体上具有地表品位低,深部品位升高的特点,在标高411 m时,品位达到最高值(Ta_2O_5品位0.438%),说明仁里矿区深部具有较大找矿潜力。本文在总结仁里矿床成矿特征和成矿规律的基础上,分析了周边及深部的找矿方向,建立了复式岩体"体中体"成矿模型。区域找矿需要重视浅部低品位伟晶岩脉的深部评价,按照"北找钽铌、南找锂"的原则开展外围找矿工作。  相似文献   

内蒙古乌拉特中旗色尔腾山岩群东五分子岩组锆石SHRIMP定年及其地质意义     

王挽琼  刘正宏  徐仲元  白新会 《吉林大学学报(地球科学版)》2019,49(4):1053-1062

色尔腾山岩群是华北克拉通中西部早前寒武纪变质结晶基底的主要组成部分,对研究华北克拉通基底演化具有十分重要的意义。色尔腾山岩群的形成时代是目前研究的热点之一,本文通过岩石学和锆石SHRIMP U-Pb定年研究,查明了内蒙古乌拉特中旗乌兰乡查干哈达地区色尔腾山岩群东五分子岩组的岩石组成和年代学特征。东五分子岩组遭受了后期岩浆和构造作用的强烈破坏,未见顶底,主要由中细粒斜长角闪岩、细粒黑云斜长片麻岩、眼球状细粒黑云斜长片麻岩、条带状细粒黑云斜长片麻岩和细粒黑云角闪片岩组成,矿物组合特征指示岩石经历了低绿片岩相-低角闪岩相变质。其中,眼球状细粒黑云斜长片麻岩出露相对较厚,与细粒黑云斜长片麻岩多呈互层状产出,局部偶夹细粒黑云斜长片麻岩。本次研究选取其中新鲜的细粒黑云斜长片麻岩进行了锆石SHRIMP U-Pb测年分析,其锆石多呈自形-半自形,发育震荡环带,主体为岩浆成因,锆石SHRIMP U-Pb定年结果为（1 930.7±9.6）Ma,代表原岩（中酸性火山岩）冷凝结晶年龄,表明东五分子岩组经历变质作用的时代应晚于1 930 Ma。  相似文献   

High to ultrahigh temperature contact metamorphism and dry partial melting of the Tasiuyak paragneiss,Northern Labrador     

R. K. Mitchell  A. Indares  B. Ryan 《Journal of Metamorphic Geology》2014,32(6):535-555

Contact aureoles of the anorthositic to granitic plutons of the Mesoproterozoic Nain Plutonic Suite (NPS), Labrador, are particularly well developed in the Palaeoproterozoic granulite facies, metasedimentary, Tasiuyak gneiss. Granulite facies regional metamorphism (M_R), c. 1860 Ma, led to biotite dehydration melting of the paragneiss and melt migration, leaving behind biotite‐poor, garnet–sillimanite‐bearing quartzofeldspathic rocks. Subsequently, Tasiuyak gneiss within a c. 1320 Ma contact aureole of the NPS was statically subjected to lower pressure, but higher temperature conditions (M_C), leading to a second partial melting event, and the generation of complex mineral assemblages and microstructures, which were controlled to a large extent by the textures of the M_R assemblage. This control is clearly seen in scanning electron microscopic images of thin sections and is further supported by phase equilibria modelling. Samples collected within the contact aureole near Anaktalik Brook, west of Nain, Labrador, mainly consist of spinel–cordierite and orthopyroxene–cordierite (or plagioclase) pseudomorphs after M_R sillimanite and garnet, respectively, within a quartzofeldspathic matrix. In addition, some samples contain fine‐grained intergrowths of K‐feldspar–quartz–cordierite–orthopyroxene inferred to be pseudomorphs after osumulite. Microstructural evidence of the former melt includes (i) coarse‐grained K‐feldspar–quartz–cordierite–orthopyroxene domains that locally cut the rock fabric and are inferred to represent neosome; (ii) very fine‐ to medium‐grained cordierite–quartz intergrowths interpreted to have formed by a reaction involving dissolution of biotite and feldspar in melt; and (iii) fine‐scale interstitial pools or micro‐cracks filled by feldspar interpreted to have crystallized from melt. Ultrahigh temperature (UHT) conditions during contact metamorphism are supported by (i) solidus temperatures >900 °C estimated for all samples, coupled with extensive textural evidence for contact‐related partial melting; (ii) the inferred (former) presence of osumilite; and (iii) titanium‐in‐quartz thermometry indicating temperatures within error of 900 °C. The UHT environment in which these unusual textures and minerals were developed was likely a consequence of the superposition of more than one contact metamorphic event upon the already relatively anhydrous Tasiuyak gneiss.  相似文献   

桐柏山南坡的韧性走滑剪切构造   总被引：2，自引：0，他引：2  

韦必则 《现代地质》1993,7(3):285-292

桐柏山南坡的韧性走滑剪切构造是大陆内部造山带在剪切体制下的典型构造之一,以多期韧性再造的叠置为特征。文中详述了它们的几何学特征、走滑剪切应变带内岩石的变形特点,并依据地质标志分析了它们的运动学方向,对它们的流变学意义及其在桐柏造山带构造演化中的作用作了初步探讨。  相似文献   

大山片麻岩地质特征及侵位机制研究     

吕鹏  曲永贵 《吉林地质》1999,18(1):32-38

大山片麻岩的原财为奥长化岗石,呈不规则状侵入柳树河子片麻岩中,年龄２７亿年左右,太古代阜平运动晚期侵位的。侵位与当时区域上大规模的韧性剪切作用密切相关。由于剪切带各相关位置的位移量的差异,形成空间,给岩浆被动就位了有利场所,形成大山片麻岩古深成岩体。  相似文献   

恒山地区部分熔融地质体填图方法的尝试     

徐朝雷  宋春玲  赵祯祥  米广尧  魏荣珠 《地质通报》1999,18(3)

五台群地层呈东西向分布在恒山东段中部,其北为高角闪岩相的恒山片麻杂岩,两者岩性呈渐变过渡关系,由此萌发出片麻杂岩是五台群地层部分熔融而来的思路。经过填图实践,总结出地层与片麻岩体之间存在着仍属地层范畴的片麻岩层这一无序岩石地层单位,并建立起它的填图标志。与地层呈渐变关系的片麻岩体外貌复杂、边界不清,不同于具有一定侵入关系、边界明显、成分均一的片麻岩体,据此划分了原地片麻岩体与异地片麻岩体两个系列。  相似文献   

Rapid cooling and geospeedometry of granitic rocks exhumation within a volcanic arc: A case study from the Central Slovakian Neovolcanic Field (Western Carpathians)          下载免费PDF全文

Milan Kohút  Martin Danišík 《Island Arc》2017,26(5)

U–Pb Sensitive High‐Resolution Ion MicroProbe (SHRIMP) dating of zircon in combination with (U–Th)/He dating of zircon and apatite is applied to constrain the emplacement and exhumation history of the youngest granitic rocks in the Western Carpathians collected in the Central Slovakian Neovolcanic Field. Two samples of diorite from the locality Banky, and granodiorite from Banská Hodru?a yield the U–Pb zircon concordia ages of 15.21 ±0.19 Ma and 12.92 ±0.27 Ma, respectively, recording the time of zircon crystallization and the intrusions’ emplacement. Zircon (U–Th)/He ages of 14.70 ±0.94 (Banky) and 12.65 ±0.61 Ma (Banská Hodru?a), and apatite (U–Th)/He ages of 14.45 ±0.70 Ma (diorite) and 12.26 ±0.77 Ma (granodiorite) are less than 1 Myr younger than the corresponding zircon U–Pb ages. For both diorite and granodiorite rocks their chronological data thus document a simple cooling process from magmatic crystallization/solidification temperatures to near‐surface temperatures in the Middle Miocene, without subsequent reheating. Geospeedometry data suggest for rapid cooling at an average rate of 678 ±158 °C/Myr, and the exhumation rate of 5 mm/year corresponding to active tectonic‐forced exhumation. The quick cooling is interpreted to record the exhumation of the studied granitic rocks complex that closely followed its emplacement, and was likely accompanied by a drop in the paleo‐geothermal gradient due to cessation of volcanic activity in the area.  相似文献   

云南金平县阿德博独居石矿床成矿时代及地质意义     

王炳华 《地质与勘探》2020,56(3):523-539

西南三江地区是我国重要的成矿区带之一,具有复合叠加成矿特征。阿德博独居石矿床位于云南省金平县境内,印度地块、哀牢山-金沙江断裂带南侧,属于哀牢山隆起的东南延伸部分。该矿床赋存于花岗质风化壳中,岩性主要有片麻状花岗岩、二长花岗岩、花岗片麻岩;矿体中主要含有独居石,少量磷钇矿、锆石、金红石、钛铁矿、榍石。岩体中片麻状花岗岩的锆石U-Pb谐和年龄为31.40±0.16Ma(MSWD=7.8),二长花岗岩的锆石U-Pb谐和年龄为34.52±0.22 Ma(MSWD=1.3),表明阿德博岩体形成于新生代古近纪,与三江地区构造体制转换阶段富碱斑岩体的成矿时期一致。片麻状花岗岩中45个锆石Hf同位素数据结果较均一,(~(176)Hf/~(177)Hf)i比值范围为0.282583～0.282712,平均为0.282633,εHf(t=31.40 Ma)范围为-6.00～-1.44,平均值为-4.21。二长花岗岩中13个锆石Hf同位素数据结果变化范围较大,(~(176)Hf/~(177)Hf)i=0.282484～0.282814(平均值为0.282681),εHf(t=31.40 Ma)=-9.43～2.22(平均值为-2.45);其中有8粒锆石的εHf(t)为负值,5颗锆石的εHf(t)为正值,暗示岩体的源区主要为地壳物质的部分熔融,可能有地幔物质的混合。  相似文献