On the Origin of Migmatites in Yunlu, Western Guangdong     

Chen Bin  Huang Fusheng Department of Geology  Peking University  Beijing Jiang M inxi 《《地质学报》英文版》1995,69(1):41-52

Partially migmatized rocks, banded migmatites, augen-banded migmatites and gneissic migmatites are developed successively from Xindong to Yunlu, Gaozhou, Guangdong Province in the Yunkai Caledonian orogenic belt at the border between Guangdong and Guangxi. Mass-balance calculations, statistical analysis of the textural relations and mineralogical and geochemical studies of the migmatites and the study of the metamorphlc setting of the Yunlu area indicate that the migmatites in the study area were primarily formed by anatexis without remarkable introduction of foreign components such as K, Na and Si and removal of Ca, Fe, Mg, etc.  相似文献   

Transforming mylonitic metagranite by open-system interactions during melt flow   总被引：3，自引：2，他引：1  

P. HASALOVÁ  P. &#;TÍPSKÁ  R. POWELL  K. SCHULMANN  V. JANOU&#;EK  O. LEXA 《Journal of Metamorphic Geology》2008,26(1):55-80

Gneisses and migmatites of the Gföhl unit (Moldanubian Zone, Bohemian Massif) range from banded mylonitic orthogneiss with recrystallized monomineralic bands, through stromatic (metatexite) and schlieren (inhomogeneous diatexite) migmatite, to isotropic nebulite (homogeneous diatexite). This sequence was classically attributed to increasing degree of anatexis. Under the microscope, the evolution is characterized by progressive destruction of the monomineralic banding that characterizes the original mylonitic orthogneiss. Throughout, the mineral assemblage is biotite–K‐feldspar–plagioclase–quartz ± garnet ± sillimanite, but the mineral compositions exhibit systematic changes with progressive disintegration of the layering. From banded orthogneiss to nebulite, the garnet composition changes systematically, Alm_75→94Prp_17→0.8Grs_2.5→1.2Sps_2→11 and X_Fe = 0.45→0.99 and for biotite, X_Fe = 0.80→1. This is consistent with a decrease in equilibration temperature and pressure of 790 °C and 8.5–6 kbar, to 690 °C and 5–4 kbar respectively. There is also a systematic change of whole‐rock composition, marked by an increase in SiO₂ (71→77 wt%) and X_Fe (0.62→0.85) and by a decrease in Al₂O₃ (16→13 wt%) and CaO (1.50→0.43 wt%). Assuming that the rocks started with the same composition, these systematic changes indicate open‐system behaviour. The predicted consequences of various open‐system processes are assessed using thermodynamic modelling. The observed variations are interpreted as being a consequence of melt flow through, and interaction with the rocks, and, to change the rock composition sufficiently, a large volume of melt must have been involved.  相似文献   

矿山沉陷区新建建筑物可行性分析     

苏仲杰  郭伟  关月洁 《中国地质灾害与防治学报》2008,19(1):54-58

论文就矿山沉陷区开采煤层上覆岩层变形规律、沉陷区形成基本特征及稳定性进行了分析,对竖向集中荷载与矩形截面竖向均布荷载作用下的建筑物荷载传播深度进行分析。通过对建造建筑物时间的选择、地基附加应力传播深度的确定,评价地表残余移动变形对地基的影响。对矿山沉陷区能否新建建筑物进行可行性分析,为地基附加应力传播范围提出分析方法,为沉陷区新建建筑物提供理论依据。论文对一工程实例进行了可行性论证分析,证明了理论的可行性并得出了重要的结论。  相似文献   

A sequence of partial melting reactions at Mt Stafford, central Australia   总被引：8，自引：2，他引：6  

J. E. GREENFIELD  G. L. CLARKE  & R. W. WHITE 《Journal of Metamorphic Geology》1998,16(3):363-378

Metasedimentary gneisses show a rapid change in grade in a 10  km wide low- P /high- T  regional aureole at Mt Stafford in the Arunta Block, central Australia. Migmatite occurs in all but the lowermost of five metamorphic zones, which grade from greenschist (Zone 1) through amphibolite (Zones 2–3) to granulite facies (Zones 4–5). The sequence of partial melting reactions inferred for metapelitic rocks is dependant upon protolith, temperature and fluid conditions. The metapelite solidus in Zone 2 reflects vapour-present melting at P ≈3  kbar and T  ≈640  °C, melting having initially been controlled by the congruent breakdown of the assemblage Crd–Kfs–Bt–Qtz. At slightly higher temperature, andalusite in leucosome formed via the reaction Kfs+Qtz+Bt+H₂O→And+melt; And+melt having been stabilized by the presence of boron. Sillimanite coaxially replaces andalusite in the high-grade portion of Zone 2. In Zone 3, large aluminosilicate aggregates in leucosome are armoured by Spl–Crd±Grt symplectites. Garnet partially pseudomorphs biotite, cordierite or spinel in high-grade portions of Zone 3. Zone 4 Grt–Crd–Opx-bearing metapsammite assemblages and garnet-bearing leucosome reflect T  ≈800  °C and P =2.2±0.9  kbar. In the model KFMASH system the principal vapour-absent melting step reflected significant modal changes related to the breakdown of the As–Bt tie-line and the establishment of the Spl–Crd tie-line; the bulk rock geochemistry of migmatite samples straddle the Spl–Crd tie-line. The aluminous bulk-rock composition of the common bedded migmatite restricted its potential to witness garnet-forming and orthopyroxene-forming reactions, minor textural and modal changes in and above Zone 3 reflecting biotite destablization in biotite-poor assemblages.  相似文献   

卫星间水平距离对双差电离层残差的影响分析     

刘卫华  吴江飞  栗广才  赵才新 《测绘工程》2016,25(7)

基于TCAR方法,对影响模糊度固定的电离层残差因素进行分析,指出同测站间基线的长短一样,差分卫星间的水平距离也能够影响双差电离层残差的大小,并用实测北斗三频数据验证。实验结果表明对17km短基线,较大的差分卫星间水平距离会降低窄巷模糊度固定的成功率;而对于72.6km的中等长度基线,当双差卫星间水平距离减小时双差电离层残差随之减小,利于窄巷模糊度的固定。  相似文献   

网络RTK基准站间的模糊度及空间相关误差解算     

梁霄  杨玲  黄涛  王延兵 《测绘工程》2016,25(1):24-28

利用载波相位双差观测值的宽巷和无电离层组合固定部分模糊度参数,并采用Kalman滤波算法估计残余的对流层延迟;然后对观测值进行改正,剔除对流层延迟误差,从而提高剩余模糊度参数的固定率;最后估计双差电离层延迟。文中采用美国CORS网的GPS数据进行实验,实验结果表明,自适应滤波算法可明显提高残余对流层延迟的解算精度和模糊度的解算效率;固定模糊度并改正对流层和电离层延迟,差分定位精度得到很大提高。  相似文献   

基于土地发展权的征地补偿价格研究——以河南省周口市为例     

陈维肖  李春妍  彭宏杰  樊鹏飞  乔璐  陈常优 《地域研究与开发》2016,(3):119-122

首先,从理论角度探讨土地发展权内在机理,分析现行征地补偿价格的不足,提出了征地补偿价格应为集体农用土地价格与土地发展权价格之和,并以此构建基于土地发展权的征地补偿定价模型;其次,以周口市为例,应用构建的定价模型及农户问卷调查分析方法,测算了各县(区)基于土地发展权的征地补偿价格,并对测算结果和现行征地补偿价格进行了对比分析;最后,提出应从法律上确保农民土地发展权的权益,并在今后征地工作中逐步改革现行征地补偿制度,构建公平合理的征地补偿分配机制。  相似文献   

苏北辐射沙洲区间流系分布格局及对大气强迫力的响应     

张蓓  堵盘军 《海洋学报》2016,38(3):49-59

苏北辐射沙洲海域由10余条主沙脊和10余条主水道组成,其沙脊群间水动力的消长决定了沙洲的生成、发展及消亡,形成了滩槽相间、水道交错的独特地貌。黄海旋转潮波与东海前进潮波交汇于沙洲中心弶港,在沙洲外围诸多流系如黄海沿岸流、苏北沿岸水和长江冲淡水等影响下,又受复杂地形和大气强迫对浅水作用的影响,沙洲间余环流结构呈现4种环流结构迥异的特征。本文利用2006-2012年间8次共23站一年四季、涵盖主要沙脊和水道间准同步调查数据,以及沙洲南部4站长达1个月以上连续观测的ADCP资料,结合吕四和洋口港海洋站气象水文数据,分析了沙洲间余流四季输运分布格局,并重点讨论和分析了沙洲南部余流与风应力的响应关系。  相似文献   

岩石破坏后的注浆固结体的力学性能   总被引：15，自引：5，他引：10  

张农  侯朝炯 《岩土力学》1998,19(3):50-53

在破裂岩石残余强度和变形性能研究的基础上,进一步开展其注浆固结体的力学性能试验研究。试验证实注浆固结后破裂岩块残余强度有不同程度的提高,同时发现其侧向变形和径向变形趋向协调,从而提高了破裂岩块的塑性变形性能,并在较大变形范围内保持稳定的承载能力。试验结果有助于解释围岩注浆加固控制巷道变形的机理。  相似文献   

论秦岭碰撞造山作用对华北石炭二叠纪海侵过程的控制     

陈世悦 《沉积与特提斯地质》1998,18(2):48-54

晚古生代—三叠纪是秦岭造山带主造山作用的碰撞造山期,其中石炭二叠纪是点接触至面接触碰撞的阶段。华北石炭二叠纪发育有４次较大规模的海侵,时代分别为Ｃ２１－Ｃ１－１２,Ｃ１－２２－Ｃ２２,Ｐ１２和Ｐ１３。岩相古地理制图及海侵沉积单元空间展布规律的分析结果表明,海侵来自华北地块南侧的秦岭残余海盆,且海侵具有由东向西逐渐推进之势。这一海侵过程是受华北地块东低西高的古地理格局及秦岭造山带以小秦岭地区为中心呈双剪刀状反向穿时碰撞造山作用控制的结果  相似文献