镇江石马杂岩体中岩石包体的成因研究   总被引：2，自引：0，他引：2  

徐夕生  周金城 《大地构造与成矿学》1993,17(1):53-61

石马杂岩体,为南京—镇江地区出露面积较大的燕山期花岗质杂岩体,具大量暗色、细粒辉石闪长质-石英闪长质岩石包体,岩浆动力学理论的应用和详细的岩相学,岩石地球化学研究表明,该杂岩体中的岩石包体是不同成分岩浆大规模对流、不均一混合机制驱动下形成的,在成因类型上属淬冷包体.  相似文献   

钨、锡流-熔分配实验结果及其矿床成因意义   总被引：4，自引：1，他引：4  

陈子龙  彭省临 《地质论评》1994,40(3):274-282

本文用实验确定了钨、锡在成分不同的花岗质熔体相与共存水热流体相的流-熔分配系数(D_(Me)~(V/L))及其与介质溶液(NaF,KF,HF,NaCl等水溶液)摩尔浓度间的函数关系。实验结果表明,钨、锡的分配行为明显不同。在相同条件下,随体系的不同,D_W~(V/L)比D_(Sn)~(V/L)大几倍至二十倍。钠和钾对钨、锡的流-熔分配行为的影响基本相同,而氟和氯对钨、锡的分配行为的影响相差甚远,花岗质熔体的主成分对D_W~(V/L)和D_(Sn)~(V/L)有复杂的影响。利用这些结果探讨与花岗岩有关的钨、锡矿床的成矿机理,得出了一些与前人不同的新认识。  相似文献   

内蒙古苏尼特左旗地区堆晶角闪辉长岩的发现及地质意义   总被引：6，自引：0，他引：6  

李玉文  邓晋福 《现代地质》1995,9(2):212-219

通过详细的野外工作和室内研究，发现苏尼特左旗附近较广泛地分布有一种主要由角闪石和外长石组成的堆晶岩，其化学成分属基性岩范畴，可定名为堆晶角闪辉长岩。这类岩体具清楚的层状构造、堆晶结构．岩石化学成分、稀土元素、结构和构造等特征均表明，该类岩石是由富水的拉斑玄武岩浆经分离结晶作用形成的，是造山带火成岩组合中的一个主要组成部分，形成于造山构造岩浆旋回的早期阶段。  相似文献   

安徽安庆月山岩体的磁组构及古地磁特征   总被引：3，自引：0，他引：3  

阎桂林  张鸣 《地球科学》1990,15(6):667-673

  相似文献   

华北克拉通南缘豫西燕山期花岗岩类的 Pb-Sr- Nd同位素地球化学特征   总被引：8，自引：0，他引：8       下载免费PDF全文

陈岳龙  张本仁 《地球科学》1994,3(3)

对华北克拉通南缘豫西燕山期具类似于板块俯冲带花岗岩成分变化规律（成分极性）的八宝山、柳关、后瑶峪花岗斑岩类的Pb、Sr、Nd同位素地球化学特征的研究,揭示了这些斑岩的主要物质来源是新太古代的太华群斜长角闪岩部分熔融产生的熔浆与地幔来源物质混合形成的产物。稀土元素含量非常低的八宝山花岗斑岩在岩石形成过程中有流体与其发生交代作用,由于交代及混合作用造成花岗斑岩类的Rb—Sr等时线多为假等时线;柳关花岗斑岩基本上完全由太华群的斜长角闪岩提供物质,豫西地区燕山期的花岗岩岩基其物质来源更为复杂,可能有宽坪群为其提供物质。  相似文献   

花岗质次火山岩的成因类型及成矿专属性   总被引：2，自引：0，他引：2  

刘家远 《岩石矿物学杂志》1987,6(2):112-120

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。  相似文献   

Advective heat transfer and fabric development in a shallow crustal intrusive granite — the case of Proterozoic Vellaturu granite,south India     

Dilip Saha  Sukanya Chakraborti 《Journal of Earth System Science》2007,116(5):433-450

Syntectonic plutons emplaced in shallow crust often contain intermediate-to low-temperature deformation microstructures but lack a high-temperature, subsolidus deformation fabric, although the relict magmatic fabric is preserved. The Proterozoic Vellaturu granite emplaced at the eastern margin of the northern Nallamalai fold belt, south India during the late phase of regional deformation has a common occurrence of intermediate-to low-temperature deformation fabric, superimposed over magmatic fabric with an internally complex pattern. But high-T subsolidus deformation microstructure and fabric are absent in this pluton. The main crystal plastic deformation and fluid enhanced reaction softening was concentrated along the margin of the granite body. Resulting granite mylonites show Y-maximum c-axis fabric in completely recrystallized quartz ribbonds, dynamic recrystallization of perthites, and myrmekite indicative of fabric development under intermediate temperature (∼ 500–400°C). The weakly-deformed interior shows myrmekite, feldspar microfracturing and limited bulging recrystallization of quartz. The abundance of prism subgrain boundaries is indicative of continuing deformation through low-temperature (∼ 300°C). The relative rates of cooling influenced by advective heat transfer and deformation of the pluton seem to control the overall subsolidus fabric development. The rapid advective heat transfer from the interior in the early stages of subsolidus cooling was followed by slow cooling through intermediate temperature window as a well-developed phyllosilicate rich mylonitic skin around the granite body slowed down conductive heat loss. Low-T crystal plastic deformation of quartz was effected at a late stage of cooling and deformation of the shallow crustal granite body emplaced within the greenschist facies Nallamlai rocks.  相似文献   

Magmatic structures in the Krkonoše–Jizera Plutonic Complex,Bohemian Massif: evidence for localized multiphase flow and small-scale thermal–mechanical instabilities in a granitic magma chamber     

Jiří Žák  Josef Klomínský 《Journal of Volcanology and Geothermal Research》2007

The present paper examines magmatic structures in the Jizera and Liberec granites of the Krkonoše–Jizera Plutonic Complex, Bohemian Massif. The magmatic structures are here interpreted to preserve direct field evidence for highly localized magma flow and other processes in crystal-rich mushes, and to capture the evolution of physical processes in an ancient granitic magma chamber. We propose that after chamber-wide mixing and hybridization, as suggested by recent petrological studies, laminar magma flow became highly localized to weaker channel-like domains within the higher-strength crystal framework. Mafic schlieren formed at flow rims, and their formation presumably involved gravitational settling and velocity gradient flow sorting coupled with interstitial melt escape. Local thermal or compositional convection may have resulted in the formation of vertical schlieren tubes and ladder dikes whereas subhorizontal tubes or channels formed during flow driven by lateral gradients in magma pressure. After the cessation or deceleration of channel flow, gravity-driven processes (settling of crystals and enclaves, gravitational differentiation, development of downward dripping instabilities), accompanied by compaction, filter pressing and melt segregation, dominated in the crystal mush within the flow channels. Subsequently, magmatic folds developed in schlieren layers and the magma chamber recorded complex, late magmatic strains at high magma crystallinities. Late-stage magma pulsing into localized submagmatic cracks represents the latest events of magmatic history of the chamber prior to its final crystallization. We emphasize that the most favorable environments for the formation and preservation of magmatic structures, such as those hosted in the Jizera and Liberec granites, are slowly cooling crystal-rich mushes. Therefore, where preserved in plutons, these structures may lend strong support for a “mush model” of magmatic systems.  相似文献   

北祁连山西段柳沟峡花岗质片麻岩锆石Ｕ-Ｐｂ法测年研究   总被引：2，自引：4，他引：2       下载免费PDF全文

郭力宇甘枝茂  李惠民 《中国地质》2002,29(2):126-128

柳沟峡花岗质片麻岩是在鱼儿红幅1∶5万区调过程中从北大河岩群变质杂体中解体出的古花岗质侵入体。通过对其进行单矿物锆石U-Pb法年龄测定,获得了(1463±74)Ma和(623±138)Ma两组年龄值。结合区调成果认为(1463±74)Ma代表古花岗质侵入体上侵就位时代,(623±138)Ma代表后期叠加的变形变质热事件时代。两组年龄的获得为北祁连山早期大陆裂解及碰撞造山作用的确定提供了直接证据。  相似文献   

冈底斯斑岩铜矿（化）带：西藏第二条“玉龙”铜矿带？   总被引：98，自引：20，他引：98  

曲晓明  侯增谦  黄卫 《矿床地质》2001,20(4):355-366

通过广泛的野外地质调查和岩石地球化学,矿床学,Re-Os同位素,硫、铅同位素的综合研究,首次比较系统地论述了雅鲁藏布江北侧冈底斯斑岩型铜矿带含矿斑岩的岩石地球化学特征和矿床的蚀变矿化特征,查明了矿化时代和成矿物质来源,阐明了该带铜 (钼、金) 多金属成矿作用与冈底斯碰撞造山带发展演化的关系.并通过与玉龙斑岩铜矿带的简要对比,指出位于雅鲁藏布江北侧的冈底斯斑岩铜矿带完全有可能成为西藏的第二条“玉龙” 铜矿带,具有形成世界级铜矿带的巨大潜力.研究表明,冈底斯斑岩铜矿带含矿斑岩属钾玄岩至高钾钙碱性岩系.地球化学上以富集大离子不相容元素 Rb、Ba、Th、Sr,亏损高场强元素Nb、Ta和重稀土元素 Yb为特点;稀土元素则为轻、重稀土分馏明显的平滑右倾型式. 矿床具有自斑岩体向外由钾化→绢英岩化→青盘岩化的蚀变分带;矿化以岩浆期后阶段形成的脉状、网脉状和细脉浸染状矿体为主,矿石矿物组合简单.含矿斑岩和硫化物具有一致的硫、铅同位素组成,硫同位素具幔源特征,铅同位素显示造山带铅特点.由南木矿区5个辉钼矿样品得出了t=(14.6±0.20)Ma的Re-Os等时线年龄,说明成矿时代与斑岩体的侵入时代 (20～14 Ma) 是一致的.  相似文献