CAJ | 학술논문

为了研究白牛厂银多金属矿床成矿作用特征,对矿区岩浆岩、围岩和矿石的稀土元素进行了ICP-MS分析测试.花岗岩稀土元素组成表现了较强的Eu负异常和弱的Ce负异常.围岩稀土元素特征表现出一定程度的热水沉积成因.矿石的稀土元素组成大致可分为两组:一组矿石表现为Eu正异常或无异常和Ce负异常,反映喷流沉积稀土元素组成特征,主要是距离花岗岩体较远的白羊矿段,指示成矿热液为温度较高(＞250℃)、相对还原的流体,另外,Eu正异常和Ce负异常同时出现,说明矿石沉淀时较高温度的流体与少量的海水发生了对流混合;另一组矿石表现出与岩浆岩一致的球粒陨石标准化稀土配分模式,显示岩浆热液叠加改造成因,主要是距离花岗岩体较近的穿心洞矿段和对门山矿段.两组矿石稀土元素组成特征总体来说随着花岗岩体距离的变化而变化.根据岩浆岩、围岩和矿石的稀土元素组成特征,白牛厂银多金属矿床由喷流沉积形成主矿体,燕山期花岗质岩浆活动对矿体部分叠加改造.
위료연구백우엄은다금속광상성광작용특정,대광구암장암、위암화광석적희토원소진행료ICP-MS분석측시.화강암희토원소조성표현료교강적Eu부이상화약적Ce부이상.위암희토원소특정표현출일정정도적열수침적성인.광석적희토원소조성대치가분위량조:일조광석표현위Eu정이상혹무이상화Ce부이상,반영분류침적희토원소조성특정,주요시거리화강암체교원적백양광단,지시성광열액위온도교고(＞250℃)、상대환원적류체,령외,Eu정이상화Ce부이상동시출현,설명광석침정시교고온도적류체여소량적해수발생료대류혼합;령일조광석표현출여암장암일치적구립운석표준화희토배분모식,현시암장열액첩가개조성인,주요시거리화강암체교근적천심동광단화대문산광단.량조광석희토원소조성특정총체래설수착화강암체거리적변화이변화.근거암장암、위암화광석적희토원소조성특정,백우엄은다금속광상유분류침적형성주광체,연산기화강질암장활동대광체부분첩가개조.
This paper investigated the mineralization characteristics of sea-floor exhalative sedimentation and magmatic hydrothermal superimposition on the Bainiuchang ploymetallic deposit by systematically analyzing the REE compositions of granites, host-rocks and ores in the deposit area using ICP-MS. The REE compositions of granites possess obvious negative Eu anomalies and weak negative Ce anomalies; the REE characteristics of host-rocks imply they derived partly from sea-floor exhalative sedimentary. According to their REE compositions, the ores can be separated into two groups: one group, collected in Baiyang segment, a segment locates relatively further from the Bozhushan granite matrix, possesses none to positive Eu anomalies and negative Ce anomalies. This ore group represents that the ore-forming hydrothermal fluid is relatively reductive and its temperature is higher than 250℃. The co-occurrence of positive Eu anomalies and negative Ce anomalies indicates that convective mixing of a small amount of seawater with the hydrothermal fluid may have happened during ore depositing on the ancient seafloor. The other group, mainly collected from Chuanxindong and Duimenshan segments, segments locates relatively closer to the Bozhushan granite matrix, has similar chondrite-normalized REE distribution pattern to that of the granite. In addition to above differences, the REE characteristics of both groups of ores vary gradually by the distances of the collecting locations to the Bozhushan granite matrix. Based on REE characteristics of the Bainiuchang Ag-polymetallic deposit, we believe that the main ore body was formed by exhalative sedimentations and was partially superimposed by the Yanshanian granitic magma activites.