Controls on P–T–t deformation path from amphibole zonation during progressive metamorphism of basic rocks (estuary of the River Vilaine, South Brittany, France)

Abstract Edenite/tremolite and edenite/magnesio-hornblende in equilibrium with plagioclase, chlorite, epidote, quartz and vapour involve several types of reactions for which K _D can be related to T and P. Thermodynamic calculation of these equilibria leads to isopleth systems. Given knowledge of the progressive changes of end-member activities in zoned Ca–Mg amphiboles (based on microprobe analyses), it is possible to construct precise pressure–temperature–time paths ( P–T–t paths) which have been followed by metabasites during polyphase metamorphism. When applied to basic rocks from the River Vilaine area, this method allows us to construct a P–T–t path that can be compared directly to the P–T–t path constructed from interbedded acid rocks (aluminous micaschists) in the same structural unit. Through time, both basic and acid rocks underwent the same complex deformation history that can be described conveniently in the L–S fabric system of Flinn. This allows us to construct a P–T–t deformation path for this structural unit.
These paths are interpreted in terms of an under/overthrusting continental collision belt (the Hercynian belt), and represent an illustration of the time delay caused by stacking of more than two crustal units.     

新发现的含铬浅闪石的矿物学研究

应用电子探针、X射线粉晶衍射和红外吸收光谱等分析手段对新发现的含铬浅闪石进行了系统研究,结果表明:其分子式为(Na0 .50 Ca0 .17K0 .0 6) 0 .73 Ca2 .0 0 (Mg3 .92 ⅥAl0 .79Cr3 0 .0 6Ti0 .0 4Fe2 0 .0 1Co0 .0 1) 4 .83 (Si6.54ⅣAl1.46) 8.0 0 O2 2 (OH) 2 ,简写为NaCa2 (Mg4Al)Si7AlO2 2 (OH) 2 ,晶胞常数为a =9.84 37(19) ,b =17.94 74 (37) ,c =5 .2 796 (15 ) ,β=10 5 .2 2 2 (17)°,V =90 4 .4 0 4 3 ,其结构中确实存在Ca原子占据A位以及Cr代Mg和Al代Si的情况,说明它为新的富钙富铬的闪石类矿物,并形成于贫硅富钙富铬的环境中,其翠绿色由铬所致,故名为含铬浅闪石。     

顽辉石陨石中A,B矿的微量元素化学意义

运用电子探针和中子活化分析方法测定了清镇和Ｂｕｓｔｅｅ顽辉石无球粒陨石中含铬硫化物相的组成和微量元素含量。正如早期的报告结果，电子探针分析结果不足１００％，表明有相当含量的轻元素（ｚ〈１０）存在。     

金矿床中“绿化”──含铬绢云母化及其找矿意义

详细研究了胶东金矿中含铬绢云母的颜色、粒径、形态、化学成分、晶体结构、光性等标型特征，提出了“红化”与“绿化”相结合的金矿找矿方法。探讨了含铬绢云母的形成机理，利用Ｃｒ元素的示踪性，揭示了胶东金矿成矿作用与成岩作用乃至矿源层的继承关系。