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长江中下游地区A型花岗岩研究 总被引:1,自引:0,他引:1
对长江中下游地区江北、江南带A型花岗岩地质地球化学特征进行综合研究.结果表明,江北、江南带A型花岗岩均由正长岩、石英正长岩和碱长花岗岩组成,均具有高硅(Si O2含量为62.1!~75.09!)和高碱(K2O+Na2O值为8.3!~10.9!)、富铝(A/CNK为1.29~1.41)、富集轻稀土、明显的Eu负异常,相对原始地幔明显富集高场强元素Zr、Nb,大离子亲石元素Rb、Th,并不同程度亏损Ba、Sr的特征,主要为A1型花岗岩.结合地球化学特征、全岩Sr-Nd同位素等资料,判断其为地幔和地壳熔融物质混合的结果.锆石测年结果表明该区A型花岗岩均形成于早白垩世128~123Ma之间,属于长江中下游晚中生代岩浆岩形成的第三阶段,处于该区岩石圈减薄和伸展的高峰期. 相似文献
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塔木素地区三叠纪正长花岗岩岩石化学特征显示其总体呈富硅、碱,高FeOT/MgO比值和10 000×Ga/Al值,贫钙、镁的特征,属准铝质-弱过铝质、高钾钙碱性系列-钾玄岩系列;轻重稀土分馏明显,Eu负异常明显,稀土曲线右倾,属轻稀土富集型;微量元素表现出Zr、Hf、K元素相对富集,而Rb、Sr、Nb、Ta、U、Ti、Cr、Co、Ni元素亏损;同时具有较高的Y/Nb和Rb/Nb值,显示A2型花岗岩的特征。结合相关花岗岩构造图解分析,塔木素三叠纪正长花岗岩为在大陆边缘正常岩浆弧上,由地壳重熔而形成的增生于大陆边缘上的花岗岩,岩浆来源应为壳幔混合。其作为新生地壳的一部分,代表了碰撞晚期或碰撞后地壳增厚、抬升、拉张的构造环境。 相似文献
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下蒿坪金矿南邻区域性大断裂和燕山晚期花岗岩基,西邻店房中型隐爆角砾岩型金矿,矿区内构造及脉岩发育,成矿地质条件良好。稀土元素分析结果显示,样品具有较高的稀土总量,矿石的稀土平均值达207.7×10~(-6),LREE/HREE为6.81~14.19,轻稀土富集,轻重稀土分异明显,其中金矿石的δEu为0.49~1.37,变化于亏损至富集的2个端元。从合峪岩体→金矿石→爆破角砾岩,稀土总量逐渐增加,暗示成矿热液对岩浆岩的后期影响。微量元素分析结果显示Au、Pb、Cd、Bi、Ag、Cu、As和Zn等亲硫元素高度富集,反映富硫还原的成矿环境。黄铁矿中Pb同位素特征显示物质来源单一,同位素指标与燕山期花岗岩十分接近。矿床成矿时间为(129±45)Ma,与合峪岩体时代相近,暗示与花岗岩有成因联系。 相似文献
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内蒙古二龙包西地区早志留世二长花岗岩地球化学特征及构造环境分析 总被引:1,自引:0,他引:1
北山地区早志留世二长花岗岩分布于塔里木板块月牙山-洗肠井构造混杂岩带南侧。通过对岩石学、岩石地球化学特征的研究,认为该岩体为准铝质高钾钙碱性系列;稀土曲线为向右缓倾的"V"型曲线,表现出明显负Eu异常;微量元素中相对亏损Ba、Nb、Sr、P、Ti,富集Rb、Th、Hf等元素,暗示了岩石形成过程中经历了较为明显的斜长石的分离结晶作用。结合区域地质资料及地球化学图解分析,二长花岗岩形成于挤压构造环境,并具有同碰撞花岗岩的特征。 相似文献
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库德尔特金矿床是东昆仑祁漫塔格新发现的一处中型金矿床,金矿赋存于花岗闪长岩中。通过对花岗闪长岩开展岩石地球化学、锆石U-Pb年代学和Hf同位素研究,探讨该矿床成岩时代、成因类型和构造环境。研究结果显示:花岗闪长岩为一套准铝质高钾钙碱性岩石系列,呈现轻稀土富集的右倾分配模式,具有较明显的负Eu异常,富集大离子亲石元素(Rb、K)、活泼不相容元素(Th、U)和LREE元素,相对亏损高场强元素(Nb、Ta、Ti、P)、HREE元素和Sr元素,成岩年龄为(242.9±1.3)Ma。结合前人研究成果,认为库德尔特花岗闪长岩是在中三叠世大洋板块俯冲与碰撞转换环境中形成的I型花岗岩。 相似文献
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韧性剪切变形条件下花岗岩中稀土元素变化特征研究 总被引:2,自引:0,他引:2
本文对郯庐断裂带南段安徽境内管店花岗岩及其韧性剪切带中的糜棱化岩石进行了主要元素和稀土元素的研究。在详细的野外工作基础上,由岩体向韧性剪切带中心系统测量地质剖面并采集有代表性的岩石样品进行室内分析研究。分析结果显示,随着岩石受剪切变形作用的加强,稀土元素呈富集的趋势。各岩石球粒陨石标准化图解表现为右倾型,即轻稀土富集型。轻稀土也是随着岩石变形作用的加强而较重稀土元素富集。全文详细探讨了韧性剪切变形作用条件下岩石中稀土元素的活化转移的原因,我们认为变质-变形-流体渗滤的联合作用是导致岩石中稀土元素活化转移的主要因素。 相似文献
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In order to get a better understanding of metallogeny, the geochemical characteristics of REE and trace element for Gejiu tin polymetallic deposits were studied by comparing concentrations of REE and trace elements in different type ores and rocks, including skarn-type ore, bedded-type ore, vein-type ore, altered granite, country rocks. Results of this study indicated that the metallogenic matters for different type ores in the study area might be derived from the same origin source, which may be mainly related to granitic activities. Furthermore, there are some differences in concentrations of REE in different ores due to their different depositiona! mechanism during that time. LREE concentrations were enriched relatively in the vein-type ores and the bedded-type ores with relatively low total REE concentrations, whereas total REE concentrations were higher in the skarn-type ores with LREE and HREE concentrations in wide variation ranges. 相似文献
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Enrichment and Release of Rare Earth Elements during Weathering of Sedimentary Rocks in Wujiang Catchments, Southwest China 总被引:1,自引:0,他引:1
Thirteen weathering profiles of sedimentary rocks such as limestone, dolomitic limestone, dolomite, sillicalite, black shale and purple sandrock from Wujiang catchments were selected for study on enrichment and release behavior of rare earth elements (REE) during weathering, and its impact on plant growth and riverine REE distribution in the catchments with methods of hierachical cluster analysis and mass balance calculation in order to set a basis for riverine material source research and agricultural production. The results show that the enrichment degree of REE in calcareous soils from the Wujiang catchments is much higher than that of limestone, yellow soil, upper continental crust (UCC), China soil (CS) and world soil (WS). The ability of enrichment and release of REE is partly controlled by distribution of REE in bedrocks, contents and adsorption ability of organic matters, clay minerals and Fe-oxides/hydroxides in weathering profiles. The REE released from weathering of carbonate rocks and clastic rocks can be absorbed and utilized by local plants. The results also reveal that release of REE and Fe mainly from weathering of carbonate rocks and partly from clastic rocks exerts an important control on riverine REE distribution. 相似文献
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Enrichment and Release of Rare Earth Elements during Weathering of Sedimentary Rocks in Wujiang Catchments 总被引:1,自引:0,他引:1
Song Zhaoliang Liu Congqiang Han Guilin Wang Zhongliang Zhu Zhaozhou Yang Song Zhaoliang 《中国稀土学报(英文版)》2006,24(3):293-293
Thirteen weathering profiles of sedimentary rocks such as limestone, dolomitic limestone, dolomite, silicalite, black shale and purple sandrock from Wujiang catchments were selected for study on enrichment and release behavior of rare earth elements (REE) during weathering, and in its impact on plant growth and riverine REE distribution in the catchments with methods of hierachical cluster analysis and mass balance calculation in order to set a basis for riverine material source research and agricultural production. The results show that the enrichment degree of REE in calcareous soils from the Wujiang catchments is much higher than that of limestone, yellow soil, upper continental crust (UCC), 相似文献
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在前人资料的基础上通过野外勘察和室内分析,对老挝国万象省纳勐铜多金属矿床地质背景进行总结,并对从该区采集的矽卡岩样品开展了地球化学特征研究,进而探究该矿床的成因及规律.主要侵入体岩性为黑云母二长花岗岩,地球化学研究表明,过铝质钙碱性花岗岩对成矿有利,Pb、Co、Sn、Mo、Ba等成矿元素可能来源于侵入体,但花岗岩并不是理想的成矿母岩.岩浆岩具有多期的特征,大部分属于Ⅰ型岛弧花岗岩.岩浆活动具有一定的规律. 相似文献
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温杖子金矿床位于辽宁省建昌县境内,为辽西地区著名的中型金矿床,矿体主要赋存于破碎蚀变岩中,受断裂控制明显。岩石地球化学研究表明:温杖子金矿区花岗闪长岩属于过铝质高钾钙碱性系列岩石,轻稀土元素富集、重稀土元素亏损,具有微弱的负Eu异常,无或极弱Ce异常,富集大离子亲石元素(Rb、K、Ba等)和化学性质活泼的不相容元素(U、Th等),亏损高场强元素(Nb、P、Hf、Zr、Ti等)和重稀土元素(Y、Yb、Lu等),具有与埃达克岩相似的岩石地球化学特征,岩浆来源于地壳和地幔物质混合源区,为火山弧花岗岩构造环境,形成于华北板块由挤压构造体制转化为伸张构造体制阶段。温杖子金矿区成矿作用经历了燕山早期、燕山中期和燕山晚期3个阶段,主成矿期为燕山晚期,其成矿作用与花岗闪长岩侵位相关,认为温杖子金矿床属于蚀变岩型金矿床。 相似文献
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Analyses of rare earth elements (REE) in gold-bearing quartz vein, granite and altered wall-rock (amphibolite) collected from Jiapigou gold belt in Southeast Jilin Province were conducted using inductively coupled plasma-mass-spectrometry (ICP-MS). The results in- dicated that the Jiapigou gold belt underwent two periods of gold mineralization: the earlier mineralization was related to the intrusion of Neoarchaean kaligranite, where the REE of earlier gold-bearing quartz veins and Neoarchaean kaligranites were typically featured by lower concentration and positive Eu anomaly; the later mineralization was related to the intrusion of the Yanshanian granite in Mesozoic, where the REE of later gold-bearing quartz veins and Yanshanian granites were typically featured by high concentration and negative Eu anomaly. However, the metallogenic mechanisms of the earlier and of the later gold mineralization periods were analogous, metallogenic materials were heterogenous with metallogenic fluids which mainly originated from magmatic hydrothermal fluids, mixed with metamorphic fluids; the metallogenic materials were mainly derived from the altered wall rock. 相似文献