下庄铀矿田一种新型交代蚀变糜棱岩铀钨矿体

通过蚀变岩重砂分析、显微镜观察及化学成分的研究,确定竹山下露天采场及七号坑采场原称“辉绿岩”实际上是一种黑云母化、角闪石化、绿泥石化、电气石化和水云母化的绿色气热交代花岗岩的蚀变岩。该绿色蚀变岩中普遍发育白钨矿化和晶质铀矿化。在下庄铀矿田中首次发现了晶质铀矿与白钨矿的共生矿体。     

Characteristics of Compositional Migration in Mylonites from the Ductile Shear Zones of the Southern Tancheng-Lujiang Fault Belt, Eastern Anhui Province

On the basis of field geology, three typical ductile shear zones in the southern part of the Tancheng-Lujiang fault belt have been chosen for a detailed study. Altogether ten samples of the tectonites have been collected for this study. The paper is focused on a comprehensive study of the tectonites in the medium-lower horizons of the ductile shear zones. The mineral compositions of the rocks are analyzed with EPMA and some typical whole-rock samples analyzed by chemical and ICP methods. Based on the comprehensive study of the characteristics of the deformation, the mineral assemblages and the changes of chemical composition of the bulk rocks, this paper presents a discussion on the relationship between the volume loss, the fluid flow and compositional changes during mylonitization of the ductile shear zones in this region. Our study shows that there are a large amount of fluids flowing through the shear zones during the process of mylonization, accompanied by the loss of rock volume and migration of el     

定结地区韧性剪切带变形特征与糜棱岩研究

定结地区位于喜马拉雅造山带中段 ,发育有多方向、多尺度、多层次、多期次的韧性剪切带。在剪切带中 ,各种韧性变形组构极为丰富 ,表明剪切带岩石的变形主要为韧性变形机制所致。变形岩石类型为花岗质糜棱岩、长英质糜棱岩和硅质糜棱岩 ;由于岩石受糜棱岩化作用程度的不同 ,在韧性剪切带中发育糜棱岩化岩石、初糜棱岩、糜棱岩及超糜棱岩 ;剪切带岩石的变形温度为 2 0 8～ 5 5 9℃。     

Geochemical and Mineralogical Studies of the Mylonite Xenoliths and Monzogranite Rocks at Wadi Abu Rusheid,South Eastern Desert,Egypt: Insights on the Genesis of Mineralization

Abu Rusheid area lie in the south of the Eastern Desert of Egypt and comprises (1) ophiolitic mélange, consisting of ultramafic rocks and layered metagabbros in metasedimentary matrix (2) cataclastic group, consisting of protomylonites, mylonites, ultramylonites and silicified ultramylonites (3) monzogranites (4) pegmatite pockets, quartz veins and post-granite dykes. Focus on the monzogranites and the xenoliths of mylonite rocks from the geochemical and mineralogical points of view introduces a new view about the genesis of the related mineralization. Geochemically, the monzogranites have a metaluminous character and were crystallized under moderate water-vapor pressure around 3 kb and temperatures of 750–800°C. The monzogranites are altered along strike-slip faults exhibiting propylitic, with slightly sodic metasomatism and record high radioactive measurements. The average uranium and thorium (U and Th) contents in fresh monzogranites, mylonite xenolith and altered monzogranites are (7.3, 21.20), (40.36, 94.82), (60.34 and 347.88 ppm), respectively. These high radioactivities are attributed to the presence of kasolite, uranothorite, cerite, fluorite, zircon, apatite and columbite. The mylonite xenolith is higher in radioactivity than the surrounding fresh monzogranites, reflecting U and Th enrichment before emplacement of the monzogranites, then the latter were subjected to right lateral strike-slip faulting with producing hydrothermal solution rich in Th and U.     

同韧性剪切断裂特征及其研究意义

同韧性剪切断裂是一种新的断裂类型,它既不同于脆性断裂,也不同于韧性剪切带。它是韧性剪切带在一定条件下发展到一定程度转化为宏观破裂的产物,在宏观、微观、地球化学等许多方面独具特征。它的研究对丰富和发展构造地质学理论、地质找矿、地震、地质灾害、工程稳定等许多方面有重要意义。     

新甘交界红柳河辉长质糜棱岩的超显微影像特征及其形成动力学环境分析

红柳河蛇绿岩中的堆晶辉长岩层具有强烈的韧性变形现象．用 Ｔ Ｅ Ｍ 观察辉石的超显微位错组态特征,其自由位错从直线状、弓弯状、环状及具尖点、三结点结构直至漫散结构的胞结构,位错壁组态表现为由直线形和环形位错排列而成的两种类型,还可见清晰的亚颗粒构造．显微与超显微特征表明,辉石以晶内位错滑移为主导变形机制．利用动态重结晶的辉石－ 斜长石矿物对讨论了糜棱岩形成的温压条件：温度大约为４２０ ℃,压力１５０ Ｍ Ｐａ ;用动态重结晶颗粒大小对古差异应力进行估算,平均为８５ ．７８ Ｍ Ｐａ．认为红柳河辉长质糜棱岩是在洋盆扩张过程中,洋壳上部冷的刚性层与下伏较热的塑性层拆离,沿拆离面韧性剪切形成的．     

P-A分形模型定量度量糜棱岩变形过程中石英微结构的变化

定量度量动力变质作用下组成糜棱岩矿物颗粒的不规则变化是一项挑战性的研究.以基于GIS的PA(周长-面积)模型定量地描述糜棱岩中具自相似性石英形态的不规则变化.研究实例是苏格兰西北地区Moine逆冲断裂带前缘变质程度不同的5种类型的糜棱岩.石英是糜棱岩的主要矿物成分,其镜下的显微图片经扫描转换成数字图像,再通过GIS技术转换成矢量图,并计算出每颗石英的周长和面积.研究结果表明,随变质程度的增加,其PA分形维数分别从1.20、1.28、1.38、1.46,逐步增加到1.60.这表明,随变质程度的增加,变形程度与动态重结晶作用加强,石英颗粒从规则到不规则.     

辽南韧性剪切带糜棱岩类质量平衡分析

辽南韧性剪切带糜棱岩类质量平衡分析表明 ,该剪切带是在一个开放体系非等化学背景下形成的。该带中物质组分的迁移活动 ,主要发生在初糜棱岩—糜棱岩阶段。并以SiO2 的大量迁出 ,TiO2 ,FeO ,MnO ,CaO ,MgO ,P2 O5的显著迁入为特征。以Al2 O3为守恒条件 ,整个剪切带从原岩到糜棱岩的质量和体积发生了 6 74 %～ 7 4 8%损失。     

论糜棱岩的分类

糜棱岩是在构造应力作用下发生明显塑性变形、具有明显的运动指向标志、集中呈带状产出的构造岩。根据实用性和目的性建立庆棱岩的描述性和成因两个分类系列。在描述性分类中,将糜棱岩分为细粒糜棱岩、中粒糜棱岩和粗粒糜棱岩３个类型。各类型再进一步分为均匀、均匀碎斑和非均匀碎斑３个亚类。在成因分类中,将糜棱岩分为低温脆一韧性糜棱岩、中温韧性糜棱岩和高温超韧性糜棱岩３个类型,再分为低温石英脆一韧性糜棱岩、中温石英韧性糜棱岩、中温石英一斜长有韧性糜棱岩及高温斜长石一钾长石超韧性糜棱岩、高温钾长石一辉石超韧性糜棱岩、高温辉石－橄榄石超韧性糜棱岩６个亚类。     

龙门山彭灌杂岩体中韧性剪切带的发现及其构造意义

本文从构造变形和断层岩的角度,运用断裂构造的新观念.通过野外宏观特征和糜棱岩的显微构造研究,证实了彭灌杂岩体中韧性剪切蒂的存在,并以构造层次原理阐述了它们对该区构造研究的意义。