摘要
在花岗伟晶岩型铀矿床中,黑云母常见于与产铀相关的围岩地层、花岗岩体和花岗伟晶岩脉之中,并且常常与晶质铀矿紧密共生,在对岩石放射性元素的还原和吸附过程中起着重要作用。选取北秦岭柳树湾花岗伟晶岩型铀矿床中围岩地层、花岗岩体、含矿花岗伟晶岩和不含矿花岗伟晶岩中的黑云母作为研究对象,通过电子探针矿物化学特征研究表明:黑云斜长片岩和不含矿花岗伟晶岩中的黑云母分别为羟金云母和羟铁云母。灰池子二长花岗岩体和含矿花岗伟晶岩中的黑云母呈现出由富铁羟金云母向富镁羟铁云母演化的过渡关系,二者显示出较好的亲缘性。随着岩浆不断演化,灰池子二长花岗岩-含矿花岗伟晶岩-不含矿花岗伟晶岩形成的温度和氧逸度不断降低,母源岩浆显示出由壳幔混合来源向单一壳源成因演化的特点。黑云母成分示踪结合区域地质背景研究表明:与柳树湾铀矿有关的灰池子二长花岗岩体、含矿花岗伟晶岩和不含矿花岗伟晶岩分别形成于板块碰撞的挤压构造环境、挤压向伸展的构造体制转换阶段以及随后与拆沉减薄有关的伸展阶段,是晚古生代北秦岭三次构造活动的浅部岩浆反应。
In pegmatite type uranium deposit,biotite widely exists in strata,granite and pegmatite and closely related to uraninite,therefore it plays a key role in absorbing and depositing radioactive elements.Biotite in strata,granites,ore-hosting and barren pegmatites in Liushuwan uranium deposit was selected for the mineral chemistry study with EPMA,it was indicated that biotite in plagioclase amphibole-schist and ore barren granitic pegmatite are phlogopite and annite,respectively.Biotite in monzogranite and orehosting granitic pegmatite bear the transitional phase minerals from Fe-rich phlogopite to Mg-rich annite with good relatedness.During the process of magmatic differentiation,the forming temperature and oxygen fugacity presented a gradually decreasing trend from monzogranite,ore hosting pegmatite to ore barren pegmatite,which suggest that the source magma evolved from the mixing of crust and mantle source type to crust source type.Based on the biotite composition characteristics and the tectonic events,it was believed that the monzogranite,ore hosting and barren pegmatite in Liushuwan deposit were formed in main compression environment of collisional orogeny,transformation setting from collisional to extension and extension setting related to the detachment of the continental slab,which is the shallow response of the third phase of Paleozoic North Qinling Orogen.
作者
曲凯
尹青青
刘行
司马献章
温国栋
张盼盼
闫国强
张超
QU Kai;YIN Qingqing;LIU Xing;SIMA Xianzhang;WEN Guodong;ZHANG Panpan;YAN Guoqiang;ZHANG Chao(Tianjin Center,China Geological Survey,Tianjin 300170,China;Sinosteel Tianjin Geological Academy,Tianjin 300181,China;Henan Provincial Nuclear Geology,Zhengzhou,Henan 450044,China)
出处
《铀矿地质》
CAS
CSCD
2019年第6期330-342,共13页
Uranium Geology
基金
国家自然科学基金项目（编号：41502033）
中国地质调查局能源矿产地质调查项目（编号：DD20190813-4、 DD20160129-3）联合资助
关键词
花岗伟晶岩型铀矿床
黑云母
矿物化学
成岩成矿
北秦岭
granitic pegmatite-type uranium deposit
biotite
mineral chemistry
petrogenesis and mineralization
North Qinling Orogen
