相山斑岩型铀矿床铀矿成矿深度和剥蚀程度多方法联合估算

Xiangshan uranium ore field is one of most important nuclear resources reserve base,plays an important role in uranium geology research field.The Xiangshan uranium deposit is a typical continental volcano rock type uranium deposit,there are three uranium ore type of volcanic lava,porphyry and eruptive breccia pipe according to the host rock in Xiangshan orefield.Have been found porphyry type uranium deposit is mainly distributed in the north of Xiangshan,there have also distribution characteristics similar to granite porphyry uranium prospecting,but progress has not been big in uranium prospecting in the south eastern area of Xiangshan.This application is intended to Xiangshan porphyry type uranium deposit as the research object,through the field characteristics of magmatic emplacement,typical mineral balance geological pressure gauge,fission track,fluid inclusions pressure gauge,and so on,multi-method joint estimation the uranium ore-forming depth and the degree of erosion after mineralization of Xiangshan have been found porphyry-type uranium deposit.Based on the field geological survey, petrography,geochemistry and isotopic geology,we have determined the basic geological characteristics of granite porphyry in the south-east Xiangshan orefield,and identified its material source and diagenetic environment.By comprehensive and system comparative study to the produce uranium granite porphyry of the northern Xiangshan orefield,to discuss the uranium mineralization possibilities in the south-east Xiangshan granite porphyry.The completion of the project is great practical and theoretical significance deepening the uranium mineralization law of Xiangshan region,to breakthrough prospecting of Xiangshan south-east region and expansion the uranium resources in the Xiangshan deep region.

相山铀矿田是我国重要核能资源储备基地之一，在铀矿地质研究领域极为重要。相山铀矿属典型陆相火山岩型铀矿床，按含矿主岩主要有火山熔岩型、斑岩型和爆发角砾岩筒型三种铀矿床类型。已发现斑岩型铀矿床较集中分布在相山矿田之北部，相山南东部地区虽分布有特征类似花岗斑岩，但铀矿找矿至今未获大的进展。本申请以相山矿田斑岩型铀矿床为研究对象，通过野外岩浆岩侵位特征、典型矿物平衡地质压力计、裂变径迹、流体包裹体压力计等多方法联合研究，对相山斑岩型铀矿床开展铀矿成矿深度和成矿后被剥蚀程度精确估算。通过野外地质调查、岩相学、地球化学、同位素地质学等的研究，厘定相山南东部花岗斑岩基本地质特征，查明其物质来源、成岩环境等。通过与相山北部产铀花岗斑岩系统对比研究，探讨相山南东部花岗斑岩铀矿成矿可能性。项目的完成对于相山地区铀成矿规律认识深化、相山南东部地区找矿突破以及相山深部铀资源量扩大具有重要的现实意义和理论意义。

相山铀矿田是我国重要核能资源储备基地之一，在铀矿地质研究领域极为重要。已发现斑岩型铀矿床集中分布在相山矿田之北部，相山南部地区虽分布有特征类似花岗斑岩，但铀矿找矿至今未获大的进展。项目通过对相山南、北部花岗斑岩岩体开展野外地质、岩相学、主微量元素、Sr-Nd-Pb同位素、成岩时代等特征的对比研究，分析其岩浆的物质来源、形成的构造环境以及其岩石成因类型，在此基础上探讨相山南部铀成矿的可能性。研究发现，相山南、北部花岗斑岩均呈肉红色或灰白色，斑状或似斑状结构，斑晶矿物主要由石英、钾长石、斜长石和黑云母组成，基质的矿物成分与特征均与斑晶相同，石英斑晶边部均被熔蚀呈次圆状，并以聚斑形式展布；钾长石自形程度相似，斜长石与黑云母等特征基本一致。岩石均富硅、富碱，属于准铝质-过铝质的钾玄岩系列及高钾钙碱性系列，具有较高的结晶分异演化的特征。微量元素原始地幔标准化蛛网图显示，岩石的Th、U、Pb、La、Rb、Nd等元素呈正异常，Ba、P、Ti、Sr等元素呈负异常，U和Th明显偏高。岩石ΣREE高于地壳，具有较强的轻重稀土元素分馏，稀土元素球粒陨石标准化配分模式图呈“海鸥型”，Eu负异常。87Sr/86Sr初始比值与大陆地壳平均值相近，ƒSm/Nd=-0.54~-0.40，εNd(t)较低，207Pb/204Pb>15.6。LA-ICP-MS锆石U-Pb定年显示，两者成岩时代相同，年龄值在132Ma~137Ma之间，属于早白垩纪时期。研究认为，相山南、北部花岗斑岩具有相同的物质来源、成因类型和形成构造环境，其岩浆均主要起源于地壳物质，岩石成因类型均属于A型花岗岩与S型花岗岩之间的过渡型（A-S型），形成环境均为由太平洋板块俯冲之后因板块后撤岩浆侵入作用形成的板内构造环境。据此认为，相山南部花岗斑岩体具有铀成矿的可能性，主要矿体可能还位于较深部，找矿未获重大突破的原因主要是深部揭露工作量不够。