摘要
甘肃寨上金矿是我国重要的卡林型金矿床,发育多种特征的黄铁矿、毒砂、黝铜矿、黄铜矿等金属硫化物。黄铁矿贯穿整个地质过程,对其进行研究可深入理解成矿作用。观察发现,黄铁矿可分为3个世代。第1世代黄铁矿为莓球状黄铁矿(Py1A)和多孔海绵状黄铁矿(Py1B)2类;第2世代中粗粒自形黄铁矿(Py2);第3世代粗粒黄铁矿(Py3)。Py1A呈莓球状,直径介于10~50μm,w(Co)/w(Ni)小于1,w(S+As)/w(Fe)大于2,部分黄铁矿因受到热液改造,莓球中w(Co)/w(Ni)大于1,w(S+As)/w(Fe)小于2;Py1B呈多孔海绵状,w(Co)/w(Ni)大于1,w(S+As)/w(Fe)小于2。Py2呈中粗粒五角十二面体,w(Co)/w(Ni)介于1.41~3.78,w(S+As)/w(Fe)由内向外逐渐升高,介于1.93~2.02,w(Au)/w(As)介于0.023~0.108。Py3呈粗粒立方体晶,周围发育石英压力影,w(Co)/w(Ni)介于1.36~1.39,w(S+As)/w(Fe)介于1.98~2.00。结合地质背景分析认为,黄铁矿微晶直接聚集形成Py1A(莓球状),或在松散状态下经胶结作用形成Py1B(多孔海绵状),并遭受热液叠加改造。Py2(中粗粒五角十二面体)由含矿热液环绕多孔海绵状核部直接结晶形成,Py3(粗粒自形立方体)由晚期热液结晶形成,并同时遭受构造变形活动。该区黄铁矿的特征对于判别地质环境有标型意义。
The Zhaishang gold deposit with various metal sulfides such as pyrite,arsenopyrite and chalcopyrite,is a critical Carlin-type deposit in Gansu Province,Northwestern China.Pyrite occurs during the whole geological processes,which is useful to understand the mineralization deeply.Pyrite is formed through the following three stages:1)framboidal pyrite(Py1 A)and porous pyrite(Py1 B),2)mid-coarser grained euhedral pyrite Py2 and 3)coarser grained euhedral pyrite Py3.Py1 A is framboidal,with a diameter of 10~50μm.It’s Co/Ni is lower than 1,and(S+As)/Fe is higher than 2.Part of the framboidal pyrite is transformed by hydrothermal fluid,so the Co/Ni is higher than 1,and S/Fe is lower than 2.Py1 B is porous,and it’s(S+As)/Fe is smaller than 2.Py2 is a mid-coarser pentagonal dodecahedral crystal with Co/Ni between 1.41 and 3.78,(S+As)/Fe between 1.93 and 2.02 rising from the inside to the outside,and Au/As between 0.023 and 0.108.Py3 is a coarser euhedral grain with quartz pressure shadows around it,Co/Ni between 1.36 and 1.39,and(S+As)/Fe between 1.98 and 2.00.Combined with the geological background,the pyrite 1 A(framboidal)is formed by the direct aggregation of pyrite micro-crystallites,indicating the sedimentary genesis.Pyrite 1 B(porous)is cemented by loose pyrite microcrystals and subjected to hydrothermal superposition reformation.The pyrite 2(mid-coarser pentagonal dodecahedral)is formed by direct crystallization of hydrothermal fluid around the porous nodules.The pyrite 3(coarser euhedral grain)is formed by late hydrothermal crystallization and transformed by deformation.The pyrite from this deposit can be a set of standards for distinguishing geological processes.
作者
赵福德
黄菲
高尚
张宝匀
孟林
ZHAO Fu-de;HUANG Fei;GAO Shang;ZHANG Bao-yun;MENG Lin(Northeastern University,Shenyang 110819,China;Shijiazhuang Tiedao University,Shijiazhuang 050043,China;Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geoscience,Langfang 065000,China)
出处
《矿物学报》
CAS
CSCD
北大核心
2019年第6期637-648,共12页
Acta Mineralogica Sinica
基金
国家自然科学基金项目(批准号：41272062)
中国地质科学院地球物理地球化学勘查研究所资助项目(编号：AS2017J13)
中央高校基本科研业务专项资金资助(编号：N170106001)
关键词
卡林型金矿
黄铁矿
多形貌
成因
标型
Carlin-type gold deposit
pyrite
polymorpholoy
genesis
typomorphic significance
