摘要
黑龙江省虎林市四平山金矿床位于那丹哈达地体东部,为该地体中规模最大的金矿床,已探明金资源量5.8 t,矿体赋存于四平山组硅质岩、硅质角砾岩以及大塔山林场组流纹岩中。为了进一步厘定成岩成矿时代,阐释成矿过程,查明成岩成矿地球动力学背景,本文在四平山金矿床进行详细的野外调查基础上,以四平山组硅质岩、硅质角砾岩和大塔山林场组流纹岩为研究对象,开展赋矿围岩LA-ICP-MS锆石U-Pb定年和全岩主微量组成测试,以及含金石英脉流体包裹体热力学分析。结果表明,大塔山林场组流纹岩(SPS-H-002、SPS-H-009)的成岩年龄分别为(134±1)Ma和(123±1)Ma,金矿化时代略晚于流纹岩的成岩时代,属于早白垩世晚期;硅质岩和硅质角砾岩具有较高的SiO2含量,富集Cu、Ni、Ba元素而贫Co元素,ΣREE含量较低,轻重稀土分异程度不明显,具有铕正异常,形成于热水沉积作用;流纹岩具有高硅、富铝、贫钛锰磷和低Zr含量,为亚碱性过铝质钙碱性-高钾钙碱性系列岩石,轻稀土富集,重稀土亏损,具有明显的铕负异常,无铈异常,属于高分异S型花岗岩,可能为亏损地幔增生的年轻地壳物质部分熔融的产物;含金石英脉中流体包裹体大小介于5~12μm之间,呈椭圆形和不规则形状成群或孤立分布,均一温度为118.7~223.4℃,盐度为0.40%~8.9%,密度为0.84~0.97 g/cm^(3),捕获压力为21.2~51.4 MPa,δD值为-113.8‰~-84.0‰,δ^(18)O_(H2O)值为-3.1‰~2.2‰,成矿流体以岩浆水为主,并显示出岩浆水与大气降水混合的特点。结合区域构造演化,认为四平山金矿床形成于碰撞后构造背景,成矿与古太平洋板块俯冲作用密切相关。
The Sipingshan gold deposit is located in the east Nadanhada terrane,which is the largest gold deposit in the terrane with a proven gold resource of 5.8 t in Hulin City,Heilongjiang Province.The ore body occurs in the cherts and silicified breccias in Sipingshan Formation,and the rhyolite in Datashanlinchang Formation.In this study,we aim to understand the metallogenic process and diagenetic and metallogenic geodynamics,and further determine the diagenetic and metallogenic ages.We conducted detailed field survey on the Sipingshan gold deposit and sampled the cherts and silicified breccias in Sipingshan Formation and rhyolite in Datashanlinchang Formation.Further,we carried out the zircon U-Pb dating using LA-ICP-MS technique and whole-rock major and trace element geochemistry on the ore-bearing surrounding rocks,and additionally we performed the thermodynamic analysis on the fluid inclusions in the gold-bearing quartz veins.The results indicate that the diagenetic ages of the rhyolite samples SPS-H-002 and SPS-H-009 in Datashanlinchang Formation are(134±1)Ma and(123±1)Ma,respectively.The gold mineralization age is slightly later than the that of the rhyolites,belonging to the late Early Cretaceous.Cherts and silicified breccias have a high SiO2 content,rich in Cu,Ni,and Ba elements but poor in Co element.Rare earth elements(REE)content is relatively lower in the rocks and the concentration difference between the light and heavy rare earth elements is not significant,with a europium positive anomaly possibly caused by hydrothermal sedimentation.Rhyolite belongs to a type of rock from subalkaline peraluminous calc-alkaline to high potassium calc-alkaline series,with high Si and Al contents but poor in Ti,Mn,P,and Zr contents.Those rocks are enriched in light REE but deficient in heavy REE,with an pronounced Eu negative anomaly but no Ce anomaly.They belong to highly differentiated S-type granite and may be the product of partial melting of young crustal material with depleted mantle accretion.The fluid inclusions
作者
何云龙
张国宾
杨言辰
冯玥
孔金贵
陈兴凯
HE Yunlong;ZHANG Guobin;YANG Yanchen;FENG Yue;KONG Jingui;CHEN Xingkai(School of Mines,Liaoning Technical University,Fuxin,Liaoning 123000,China;Department of Earth Science and Engineering,Shanxi Institute of Technology,Yangquan,Shanxi 045000,China;College of Earth Sciences,Jilin University,Changchun,Jilin 130061,China;Jiangsu Coal Geophysical Prospecting and Surveying Team,Nanjing,Jiangsu 210000,China)
出处
《现代地质》
CAS
CSCD
北大核心
2024年第1期128-153,共26页
Geoscience
基金
中国地质调查局项目(1212011120342)
辽宁省科技厅面上基金项目(20170540428,201601370)
辽宁省教育厅面上基金项目(LJ2019JL027)。
