Empirical garnet–muscovite geothermometry in low-grade metapelites, Selwyn Range (Canadian Rockies)     

A. HYNES  R.C. FOREST 《Journal of Metamorphic Geology》1988,6(3):297-309

Abstract Partitioning of Fe and Mg between garnet and phengitic muscovite was calibrated as a geothermometer by Green & Hellman (1982) using experimental data at 25–30 kbar. When the thermometer is applied to pelites regionally metamorphosed at pressures of between 3 and 7 kbar it yields temperatures much higher than those from the garnet–biotite thermometer. A new empirical calibration is proposed for use with such rocks, with particular application where garnet occurs at lower grades than biotite. The new calibration is where K is given by: In K = In K _d and X _ii are mole fractions in the garnets.
The calibration was derived from comparison with the garnet–biotite thermometer of Ferry & Spear (1978), assuming no pressure-dependence for the partitioning between garnet and muscovite, no ferric iron partitioning, ideal mixing in muscovite, and the garnet mixing model of Ganguly & Saxena (1984) modified for a non-linear Ca effect. This latter garnet mixing model was selected because it gave the geologically most reasonable results. It has not proved possible to distinguish a pressure effect from a ferric-iron effect.
Despite the simplifying assumptions used to derive the calibration, it yields temperatures generally within 15°C of those given by the garnet–biotite thermometer, and has been used to supply thermometric data in a low-grade region of the Canadian Rockies.  相似文献   

苏鲁超高压变质带东海青龙山高压正片麻岩中白云母的^40Ar／^39Ar年代学研究   总被引：7，自引：1，他引：7  

陈文 李曙光张彦  刘新宇 《地质论评》2003,49(5):537-543

作为东海青龙山榴辉岩围岩的高压变质的正片麻岩，其白云母的常规^40Ar／^39Ar年龄和Rb—Sr、Sm—Nd年龄一致，激光微区Ar同位素分析表明，白云母的Ar同位素分布也是均匀的。由此得出的初步结论是：①高压变质的正片麻岩中的白云母中不含过剩Ar，这类矿物可以作为^40Ar／^39Ar同位素测年的对象；②青龙山榴辉岩中的白云母含大量过剩氩，而作为其围岩的超高压正片麻岩中的白云母却不含过剩氩，这一事实证明了榴辉岩中白云母的过剩氩不是来自围岩，而是榴辉岩自身继承的。  相似文献   

Origin of Li-F-rich granite: Evidence from high P-T experiments   总被引：2，自引：0，他引：2  

LI Fuchun    ZHU Jinchu  RAO Bing  JIN Zhangdong & ZHANG Linsong . School of Resource  Environment Sciences  Nanjing Agriculture University  Nanjing  China  . State Key Laboratory for Mineral Deposits Research  Nanjing University  Nanjing  China  . Nanjing Institute of Geography  Limnology  Chinese Academy of Sciences  Nanjing  China 《中国科学D辑(英文版)》2004,47(7):639-650

In South China and some regions around the world, there is a special type of rocks. These rocks are usually ultra-acidic, peraluminous, rich in Na and volatile components, such as H2O, F, B and P, and with higher concentrations of lithophile rare metal elements, including Li, Rb, Cs, Be, Ta, Nb, Sn, W, etc. Rocks of this type are commonly called Li-F-rich, rare-metal bearing granitic rocks, or Li-F granites for short[1]. The economic importance and distinct forma-tion mechanism of Li-…  相似文献   

白云母八面体位置中杂质阳离子和OH伸缩振动频率的关系     

袁晏明  张保民 《矿物学报》1986,(4)

本文着重讨论了利用白云母红外光谱OH伸缩振动频率测定其八面体位置中杂质元素(Fe~(3+)+Mg+Fe+Ti+Mn)的含量。从实验结果来看,用白云母红外吸收光谱的OH伸缩振动频率求其八面体位置上杂质元素的含量是可行的,且具有速度快、用样量少等特点,能得到较满意的结果。  相似文献   

一种白云母/蒙皂石1:1规则间层矿物的初步研究   总被引：1，自引：0，他引：1  

张荣英  吴方启 《岩石矿物学杂志》1987,6(2):163-170

在湖北随县长岭地区变钠长辉绿岩与绢云母千枚岩接触带中,产出一种青灰色粘土矿物。经X射线衍射、红外、热分析、电镜观察及化学分析等方法研究,证明该矿物是一种二八面体白云母与二八面体蒙皂石的1:1规则间层粘土,(K_2O含量达到4.97%)。风干样的00l衍射具有良好的整数倍关系,δ=0.059,VC=0.239,d_(060)=1.503,a_0=5.20,b_0=9.02,c_0sinβ=24.70并依据化学分析值计算出该矿物的化学结构式。  相似文献   

川西地区微晶白云母的矿物学特征研究   总被引：6，自引：3，他引：6  

林金辉  汪灵  邓苗  叶巧明  刘菁  常嗣和  范良明 《矿物岩石》2005,25(3):14-17

川西地区微晶白云母是一种新型白云母资源,其主要化学成分S iO245.7%,A l2O330.51%,K2O 11.63%,H2O 4.53%,与白云母的化学成分理论值接近,主要杂质离子F e,M g等以类质同象置换八面体中的A l3+。呈微细薄板状结晶形态,粒径小于10μm,一般1μm~5μm,平均5.5μm,厚度平均0.8μm,径厚比值小,平均6.9。结晶程度高,水化程度低或几乎未水化,不含蒙脱石间层矿物。微晶白云母的晶胞参数a=0.520 01 nm,b=0.906 33 nm,c=2.003 96 nm,α=90.00,°=β95.79,°γ=90.00,°属2M1型白云母,在结构矿物学上显示出与水云母和绢云母具有一定的差异性。  相似文献   

TiO2-白云母纳米复合材料的制备及其表面化学特征   总被引：3，自引：1，他引：3  

宋功保  彭同江  万朴  李博文 《矿物学报》2002,22(1):1-8

TiO2－白云母纳米复合材料属纳米薄膜材料，具有优异的珠光效应。本文利用化学液相沉积法制备出不同类型（单覆层、多覆层）的TiO2－白云母纳米复合材料，并利用扫描电子显微镜（SEM）和粉晶X射线衍射（XRD）、X射线光电子能谱（XPS）等手段对其进行了分析。SEM分析显示：所制备的TiO2－白云母纳米复合材料TiO2的颗粒直径在20－60nm之间，且颗粒均匀、界限清晰，表面平整。XRD分析表明：导晶剂Sn^4 对于提高TiO2向金红石转化起到了重要作用。XPS研究发现TiO2纳米镀层除Ti、O外还有以类同像替代Ti^4 形式存在的导晶离子Sn^4 和由载体白云母扩散的Si、Al、K成分。同时，表面O不足，偏离TiO2理想组成；随TiO2纳米镀层厚度的，TiO2逐渐接近理想成分；并且O（ls)、Ti(2p)向高结合能漂移，结合能增大，次外层比最外层组分具有较强的化学键合，最外层组分则表现出一定的化学活性。  相似文献   

白云母／二云母花岗岩形成与陆内俯冲作用   总被引：46，自引：0，他引：46  

邓晋福  赵海玲 《地球科学》1994,19(2):139-147

讨论了白云母／二云母花岗岩的机成机制及其与陆内俯冲作用的成生联系。以高喜马拉雅地区为例，从地质学、岩石学、地球化学、实验岩石学和地球物理学等多方位论述了白云母花岗岩形成过程的主要约束，提出并论证了一个比较合理的陆内俯冲带热结构与白云母／二云母花岗岩形成的成因模型，通过分析，得出了一个重要的新结论：白云母花岗岩的形成是陆内俯冲作用的结果。  相似文献   

The effects of ferromagnesian components on the paragonite-muscovite solvus: a semiquantitative analysis based on chemical data for natural paragonite-muscovite pairs   总被引：2，自引：0，他引：2  

C. V. GUIDOTTI  F. P. SASSI  R. SASSI  J. G. BLENCOE 《Journal of Metamorphic Geology》1994,12(6):779-788

Chemical data for 139 natural paragonite-muscovite (Pg-Ms) pairs illustrate the effects of ferromagnesian components on the P-T-X topology of the Pg-Ms solvus. The pairs were selected on the basis of: reasonably accurate knowledge of the P-T conditions of formation; evidence for close approach to equilibrium at peak metamorphic conditions; exclusion of pairs in which paragonite contains more than 5 mol% margarite; and exclusion of pairs from polymetamorphic rocks that contain more than one set of cogenetic Pg-Ms pairs. Graphical analysis reveals considerable scatter in the data; nevertheless, it is evident that the muscovite limb of the solvus shifts markedly toward end-member muscovite with increasing pressure from approximately 7 kbar to 21 kbar. This shift is attributed to a pressure-induced increase of the ferromagnesian content of muscovite, which increases the size of the XII alkali site - to the effect that K is more readily accommodated than Na. The data also suggest that the paragonite limb of the solvus migrates slightly toward end-member paragonite with increasing pressure. Broadening of the Pg-Ms solvus with increasing pressure reflects increasingly nonideal Na-K mixing as the phengite content of muscovite increases. Due to the wide scatter of data for Pg-phengitic-Ms pairs, it is concluded that, at the present time, Pg-Ms solvus thermometry is only viable for quasibinary Pg-Ms pairs.  相似文献   

扬子大陆的陆内俯冲与大陆的缩小──由白云母（二云母）花岗岩推导     

邓晋福  赵海玲  莫宣学  刘厚祥  罗照华 《高校地质学报》1995,(1)

本文简要地论述了白云母（二云母）花岗岩是陆内俯冲的岩石学记录。华南大陆与天水－雅江地带广泛分布中生代王云母花岗岩侵作入体，已有的同位素年龄范围为２４５～１２２Ｍａ，与此同时，它们两侧的扬子大陆发育前陆褶皱带，这种成对性及其构造配置表明，扬子大陆曾向华南大陆与松潘—甘孜褶皱带发生过陆内俯冲作用。基于二云母花岗岩带的总宽度（约６５０ｋｍ），估算扬子大陆最小的总俯冲量（指宽度）至少为６５０ｋｍ，扬子大陆现今宽度约６８０ｋｍ，这样，扬子大陆在中生代时期由于陆内俯冲作用缩小了约一半；另一可能方案是，消失的主要是夹持于扬子大陆与江南造山带之间的一个微大陆。扬子大陆与秦岭造山带之间的壳内构造边界不具陆内俯冲性质，而是逆冲推复一走滑构造带。在大地构造单元上，江南造山带与龙门山造山带应分属两个上叠大陆，而不属于扬子大陆。华南中生代造山带内侧属于高喜马拉雅型陆内俯冲带（缝合带内无蛇绿岩伴生），而不是雅鲁藏布江型（缝合带内有蛇绿岩伴生）。陆内俯冲作用是华南大陆形成的主要机制之一。此外，它经受过晚元古代和加里东期陆内俯冲事件，可能属于雅鲁藏布江型。多次陆内俯冲和白云母（二云母）花岗岩的形成导致亲陆壳金属元素富集，可能是华南Ｗ－Ｓｎ  相似文献