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   

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   

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   

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   

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   

Alteration at the Olympic Dam IOCG–U deposit: insights into distal to proximal feldspar and phyllosilicate chemistry from infrared reflectance spectroscopy     

A. J. Mauger  K. Ehrig  A. Kontonikas-Charos  C. L. Ciobanu  N. J. Cook  V. S. Kamenetsky 《Australian Journal of Earth Sciences》2016,63(8):959-972

Twenty thousand metres of diamond drill core representing a 14 km cross-section from weakly to intensely altered Roxby Downs Granite through the Olympic Dam Breccia Complex, host to the Olympic Dam iron-oxide–copper–gold–uranium deposit in South Australia, was analysed using the HyLogger-3 spectral scanner. Thermal and shortwave infrared spectroscopy results from 30 drill holes provide insight into the spatial relationships between quartz, orthoclase–microcline, albite–oligoclase and progressively changing sericite and chlorite compositions. The relative proportions of quartz, feldspars and phyllosilicates were mapped with thermal infrared spectroscopy. Variations in the chemistry of sericite and chlorite were extracted by proxy from their shortwave infrared spectral response, together with their relative spatial distribution. HyLogger scanning has revealed four deposit-scale mineralogical trends, progressing from least-altered Roxby Downs Granite into mineralisation where most of the feldspar has been replaced by sericite + hematite + quartz: (1) a progressive Al–OH wavelength shift of 2205 nm to 2210 nm for sericite, followed by a spatially rapid reversal corresponding to lower phengite/muscovite abundance ratios; (2) progressive Mg/Fe–OH wavelength shift of 2248 nm to 2252 nm reflecting an increase in the Fe:Mg ratio of chlorite; (3) increasing ratio of microcline to orthoclase followed by a rapid decrease; and (4) slightly decreasing ratio of albite to oligoclase followed by plagioclase destruction prior to albite replacement by sericite. The HyLogger feldspar results support recent petrographic evidence for hydrothermal albite and K-feldspar at the Olympic Dam deposit, not previously reported. The spectral results from continuous HyLogger scans also show that the microscopic observations and proposed feldspar replacement reactions are not locally isolated phenomena, but are applicable at the deposit and regional-scale. A modified quartz–K-feldspar–plagioclase ternary diagram utilising mineralogy interpreted from HyLogger thermal infrared spectra (QAP_TIR) diagram along with supporting data on the abundance ratios of orthoclase/microcline and albite/plagioclase, and the wavelength shifts in characteristic absorption features for sericite and chlorite, can be used as empirical vectors towards mineralisation within the Olympic Dam mineral system, with potential application to other IOCG ore-forming systems. Intrusion of Gairdner Dyke Swarm dolerite dykes into sericite ± hematite altered Roxby Downs Granite results in retrograde albite–chlorite–magnetite alteration envelopes (up to tens of metres thick) overprinting the original sericite ± hematite alteration zone and needs to be carefully evaluated to ensure that such areas are not falsely downgraded during exploration.  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   

内蒙古沙麦钨矿白云母40Ar/39Ar年龄及其地质意义     

吴皓然 《地质与勘探》2022,58(4):798-808

内蒙古沙麦钨矿床位于中亚造山带东段（或称兴蒙造山带）,矿体主要赋存在黑云母二长花岗（斑）岩内,主要矿化类型为伟晶岩型和云英岩型。本文利用40Ar/39Ar同位素测年方法对沙麦钨矿成矿阶段形成的白云母进行了年龄测定,获得白云母Ar-Ar坪年龄为138.4 ± 0.84 Ma,对应的正、反等时线年龄分别为137.32 ± 0.73 Ma和137.35 ± 0.73 Ma。所测坪年龄与正反等时线年龄具有很好的一致性,可以代表矿床钨矿体的形成年龄,表明该矿床的形成与沙麦地区燕山晚期的岩浆活动有关,这与区域上的成矿事件相吻合。结合区域地球动力学背景的研究成果,认为沙麦钨矿床形成于陆-陆碰撞造山后的陆内伸展环境。  相似文献   

云南个旧锡铜多金属矿区云母~(40)Ar/~(39)Ar年龄及其地质意义     

李宝龙  朱德全  邢香粉  赵磊  贾丽辉  刘昱恒 《地质通报》2015,34(12):2315-2324

云南个旧是全球最大的锡铜多金属矿区,主要成矿作用是与燕山期花岗岩密切相关的岩浆-热液体系。矿区内铜矿的主要矿床类型为变玄武岩型层状铜矿和接触带型铜矿。赋存于花岗岩体的凹陷部位,接触带型铜矿体和氧化型矿体的精确年龄尚未有报道。以老厂矿田内与铜矿体同期的等粒花岗岩脉中的黑云母和与氧化矿同时形成的白云母作为研究对象,利用常规~(40)Ar/~(39)Ar同位素定年方法,获得了黑云母和白云母的~(40)Ar/~(39)Ar坪年龄分别为82.47±0.49Ma和76.17±0.42Ma,相应的正等时线年龄为82.38±0.48Ma和76.07±0.66Ma,反等时线年龄为82.38±0.49Ma和76.07±0.73Ma。结合野外地质接触关系和矿区内其他年代学结果认为,黑云母的~(40)Ar/~(39)Ar年龄82.38±0.48Ma可以代表接触带型铜矿体的形成年龄,也揭示了新山花岗岩体形成后的快速冷却作用过程;白云母的~(40)Ar/~(39)Ar年龄76.07±0.73Ma指示了氧化型矿体的形成年龄,也记录了矿区内与甲介山同期的南北向断裂的晚期活动时限。该年龄与个旧锡铜多金属矿床的成矿时代一致。  相似文献