新疆西昆仑中太古界古陆核的确定及地质意义   总被引：3，自引：0，他引：3  

郭新成  郑玉壮  高军  朱志新 《地质论评》2013,59(3):401-412

原赫罗斯坦岩群为一套无序变质核杂岩,岩性为混合岩化花岗质片麻岩、紫苏辉石麻粒岩等。岩石组合及地球化学特征都具TTG岩石特征。采用LA-ICP-MS方法测定锆石U-Pb年龄值3137.3±4.1Ma,反映其时代为中太古代,代表赫罗斯坦杂岩原岩生成年龄。由此说明,塔里木南缘铁克里克地区存在太古宙大陆核,为新疆境内所发现的最古老岩系之一。  相似文献   

中国南极火成岩数据库数据结构和数据标准化的研究          下载免费PDF全文

尚如相  李德兴 《极地研究》1995,7(3):107-114

根据南极火成岩信息和数据类型多、数据关系复杂、样品间数据完整性和精度差异大的特点，中国南极火成岩数据库划分为主库、来源文献、岩体地质学、岩石学、主要氧化物、稀土元素、痕量元素和同位素８个数据库。通过岩体系统号、样品系统号和来源文献号三个字段使８个数据库相互关联。中国南极火成岩数据库包括了１４０多个基本字段，存储火成岩岩石描述信息和分析数据。根据国内外火成岩数据标准化的现状的分析，中国南极火成岩数据库采用了国际地科联岩石学数据库分委会规定的标准词汇和代码，并利用代码－名词术语转换技术改善了用户界面  相似文献   

Effect of sub‐core scale heterogeneities on acoustic and electrical properties of a reservoir rock: a CO2 flooding experiment of brine saturated sandstone in a computed tomography scanner     

Binyam L. Alemu  Eyvind Aker  Magnus Soldal  Øistein Johnsen  Per Aagaard 《Geophysical Prospecting》2013,61(1):235-250

The effect of sub‐core scale heterogeneity on fluid distribution pattern, and the electrical and acoustic properties of a typical reservoir rock was studied by performing drainage and imbibition flooding tests with CO₂ and brine in a laboratory. Moderately layered Rothbach sandstone was used as a test specimen. Two core samples were drilled; one perpendicular and the other parallel to the layering to allow injection of fluids along and normal to the bedding plane. During the test 3D images of fluid distribution and saturation levels were mapped by an industrial X‐ray CT‐scanner together with simultaneous measurement of electrical resistivity, ultrasonic velocities as well as amplitudes. The results showed how the layering and the flooding direction influenced the fluid distribution pattern and the saturation level of the fluids. For a given fluid saturation level, the measured changes in the acoustic and electrical parameters were affected by both the fluid distribution pattern and the layering orientation relative to the measurement direction. The P‐wave amplitude and the electrical resistivity were more sensitive to small changes in the fluid distribution patterns than the P‐wave velocity. The change in amplitude was the most affected by the orientation of the layering and the resulting fluid distribution patterns. In some instances the change due to the fluid distribution pattern was higher than the variation caused by the change in CO₂ saturation. As a result the Gassmann relation based on ‘uniform' or ‘patchy' saturation pattern was not suitable to predict the P‐wave velocity variation. Overall, the results demonstrate the importance of core‐imaging to improve our understanding of fluid distribution patterns and the associated effects on measured rock‐physics properties.  相似文献   

Exploring the potential of luminescence methods for dating Alpine rock glaciers     

《Quaternary Geochronology》2013

Rock glaciers contain valuable information about the spatial and temporal distribution of permafrost. The wide distribution of these landforms in high mountains promotes them as useful archives for the deciphering of the environmental conditions during their formation and evolution. However, age constraints are needed to unravel the palaeoclimatic context of rock glaciers, but numerical dating is difficult. Here, we present a case study assessing the potential of luminescence techniques (OSL, IRSL) to date the inner sand-rich layer of active rock glaciers. We focus on the signal properties and the resetting of the signal prior to deposition by investigating single grains. While most quartz shows low signal intensities and problematic luminescence characteristics, K-feldspar exhibits much brighter and well-performing signals. Most signals from plagioclases do not show suitable properties. Luminescence signals far below saturation indicate distinct but differential bleaching. The finite mixture model was used to determine the prominent populations in the equivalent dose distributions. The luminescence ages represent travel times of grains since incorporation into the rock glacier and hence, minimum ages of rock glacier formation. Luminescence ages between 3 ka and 8 ka for three rock glaciers from the Upper Engadine and Albula region (Swiss Alps) agree well with independent age estimates from relative and semi-quantitative approaches. Therefore, luminescence seems to have the potential of revealing age constraints about processes related to the formation of rock glaciers, but further investigations are required for solving some of the problems remaining and reducing the dating uncertainties.  相似文献   

关于重新启用“斜峪关岩群”问题的探讨   总被引：1，自引：0，他引：1  

赵陕兰  程婷  赵选社 《陕西地质》2012,30(1):1-5

分布于陕西省眉县斜峪关地区的斜峪关岩群与分布在豫陕交界的二朗坪群,处于古元古代隆起北侧的同一构造带上不同位置的构造块体,二者时代一般被限定在523～948 Ma。但二者岩石组合存在着明显的差别,构造环境具有一定差异。斜峪关岩群以中性火山岩为主,夹中酸性火山岩及少量基性火山岩。二朗坪群在陕豫交界发育拉斑玄武岩系列和钙碱性系列基性岩,且伴生较多的中酸性火山岩;南阳盆地以东,为基性和酸性火山岩,并以拉斑玄武质系列岩石为主,伴有相当数量的钠质火山岩,具类似的双模式岩套。前者岩石组合清楚、建造特征相近,时代归属和构造意义明确,具有一定的区域分布性,根据定名优先原则,建议重新启用斜峪关岩群。重新启用斜峪关岩群对研究与分析北秦岭岩石构造格架及地质演化史具有重要地质意义。  相似文献   

西北半干旱地区岩屑地球化学异常提取方法的研究          下载免费PDF全文

范小军  陈冲  王晓刚 《江苏地质》2012,36(1):23-32

西北地区主要发育残山丘陵地貌。风成砂、急雨过后的黄土硬壳以及下伏膏岩层的普遍发育在一定程度上影响了地球化学勘查数据的代表性,也给异常的提取和解释带来了困难。针对这种特殊的自然景观和地质背景,以西北半干旱地区——阿拉善某地为例,介绍了工作区地质特征,用传统的统计学方法、趋势面法、滑动平均法提取相关元素地球化学异常,在此基础上结合地质矿产资料进行综合对比,探讨了较为适合半干旱地区地球化学勘查数据处理的方法。  相似文献   

东川石庄铅锌矿成矿模式   总被引：1，自引：0，他引：1  

马能 《云南地质》2012,(1):125-127

铅锌矿赋存于上震旦统灯影组及下寒武统筇竹寺组白云岩、砂质板岩中。特富矿体是由于成矿流体的快速迁移而形成,在受控的断裂带中过饱和流体以充填方式快速沉淀所致。  相似文献   

普朗含矿斑岩岩体岩相、稳定同位素特征     

徐伯恩  罗诚 《云南地质》2012,(2):171-176

赋矿的普朗含矿复式斑岩体,具典型斑状特征及铜、钼、铁成矿专属性,由边缘到中心具石英闪长玢岩→石英二长斑岩演化关系,硅化钾化、绢英岩化蚀变与铜矿关系密切,尤以石英二长斑岩蚀变和矿化作用最强烈。硫同位素表明岩体属幔-壳源硫特征,铅同位素显示岩体铅集中分布于造山带演化线附近及下地壳、造山带、岛弧重叠区的特征。  相似文献   

冀北丰宁县茶棚银矿床成矿模式     

李会恺  张翔君 《云南地质》2012,(3):413-416

茶棚银矿属与隐伏岩体/次火山岩有关的浅成低温热液矿床。侏罗系盖层继承下伏基底变质岩系中成矿元素的高背景;隐伏岩体/次火山岩提供热源和部分物源;近SN向断裂为元素富集提供成矿空间。研究成果可以指导同类浅剥蚀区隐伏矿体的找矿工作。  相似文献   

西藏那曲县北聂荣微地块聂荣岩群中斜长角闪岩——Rodinia超大陆裂解的地质纪录   总被引：7，自引：0，他引：7  

辜平阳  李荣社  何世平  查显锋  于浦生  时超  潘术娟  王轶 《岩石矿物学杂志》2012,31(2):145-154

西藏那曲县北聂荣微地块聂荣岩群中斜长角闪岩原岩恢复为正斜长角闪岩,地球化学特征显示岩石属于拉斑系列基性火山岩,具有轻稀土元素富集、重稀土元素亏损的右倾型稀土元素配分模式。岩石富集大离子亲石元素Rb、Ba及高场强元素Nb、Ta,Sr、Th和U呈现明显的负异常,在构造环境判别图解中样品均投到板内玄武岩区,具有与裂谷火山岩相似的地球化学特征。通过高精度的LA-ICP-MS(激光剥蚀等离子体质谱仪)锆石微区原位U-Pb同位素测年,西藏那曲县北聂荣微地块聂荣岩群片麻状斜长角闪岩中获得863±10 Ma的谐和年龄,为原岩(基性火山岩)的形成时代,说明聂荣岩群形成于新元古代早期。该年龄相当于Rodinia超大陆裂解的地质记录。此外,还获得了2 539~1 006 Ma之间的捕获锆石年龄信息。  相似文献