柴北缘中段地球化学特征及铬的成矿潜力评价  

Geochemical characteristics and Cr metallogenic potential evaluation of the middle section of the northern margin of the Qaidam Basin

作　　者：陈熙 安朝 张文权 徐云甫[3] 马瑛 史连昌 陶志华 CHEN Xi;AN Zhao;ZHANG Wen-Quan;XU Yun-Fu;MA Ying;SHI Lian-Chang;TAO Zhi-Hua(No.1 Bureau of China Metallurgical Geology Bureau,Sanhe 065201,China;Qinghai Provincial Geological Survey Bureau,Xining 810100,China;Qinghai Geological Survey Institute,Xining 810100,China;The Fifth Geological Exploration Institute of Qinghai Province,Xining 810100,China;The Second Bureau of Qinghai Nonferrous Metals Geological Exploration,Xining 810100,China)

机构地区：[1]中国冶金地质总局一局,河北三河065201 [2]青海省地质调查局,青海西宁810100 [3]青海省地质调查院,青海西宁810100 [4]青海省第五地质勘查院,青海西宁810100 [5]青海省有色第二地质勘查院,青海西宁810100

出　　处：《物探与化探》2023年第2期353-364,共12页Geophysical and Geochemical Exploration

基　　金：青海省地质勘查基金项目“青海省柴周缘主要矿集区矿产资源深部勘查方法技术示范研究”(2019048001ky001)。

摘　　要：本文在提取柴北缘中段不同比例尺(1∶5万水系沉积物测量、1∶2.5万地球化学测量)59238个原始数据的基础上,进行了数理指标统计和多元统计的叠加分析,以期从区域角度寻找元素组合关系以及判断主成矿元素,为后续矿产工作提供基础支撑。根据统计显示,该区Au、W、Cr 3种元素各项数理指标显示了较强的成矿潜力,结合多元统计分析及区内已有的成矿事实,认为该区除了构造蚀变岩型、热液型金矿的产出外,寻找镁质超基性岩有关的铬矿潜力巨大。考虑到局部Cr整体背景值较高等因素,以传统X+2σ(129×10^(-6))或累积频率85%(142.9×10^(-6))的异常下限划分方法不能满足该区局部异常的圈定需求,故引用1/4浓幅分位值(234×10^(-6))提高异常下限,不仅圈定出浓集中心具有明显带状分布的异常多处,而且剔除了多数弱小异常。综合地、物、化成果,推断出进一步寻找铬矿的有利地段,划分出了4个成矿有利地段及5个找矿靶区。This study extracted 59238 pieces of original data on different scales(1∶50000 stream sediment surveys and 1∶25000 geochemical surveys)of the middle section of the northern margin of the Qaidam Basin.Based on these data,this study conducted the superposition analysis of mathematical index statistics and multivariate statistics,aiming to discover the element association relationship and determine the major metallogenic elements in the region and provide basic support for subsequent mineral work.According to the statistics,the mathematical indexes of Au,W,and Cr in the study area show great metallogenic potential.Combined with the multivariate statistical analysis and existent metallogenic facts,the authors of this study believed that the study area has the great potential for the prospecting of chromium deposits associated with ultramafic rocks besides tectonic altered rock-type and hydrothermal gold deposits.Owing to the relatively high overall background value of local chromium(Cr)element,the traditional method using X+2σ(129×10^(-6))or the cumulative frequency 85%(142.9×10^(-6))used to delineate the anomaly threshold cannot meet the requirement for delineating local anomalies in the study area.Therefore,this study improved the anomaly threshold using the 1/4 concentration grading value(234×10^(-6)).As a result,many anomalies exhibiting significant zonal distribution in the concentration center were delineated,and most weak anomalies were eliminated.Based on the geological,geophysical,and geochemical results,this study inferred zones favorable for the further exploration of chromium deposits and determined four favorable metallogenic zones and five prospecting areas.

关 键 词：1:2.5万地球化学测量 Cr 数理统计分析 成矿潜力 柴北缘中段 

分 类 号：P632[天文地球—地质矿产勘探]