甘肃早子沟金矿床地球化学联合广域电磁法的深部找矿预测
Deep prospecting prediction using integrated geochemistry and wide field electromagnetic method in the Zaozigou Gold Deposit, Gansu
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摘要: 早子沟金矿床是西秦岭造山带最大的金矿床之一。然而,随着开采深度增加,勘探难度越来越大。尽管深部资源潜力巨大,但对深部矿体的展布认识不清。通过开展地球化学联合广域电磁法工作,在早子沟金矿床开展深部成矿预测研究并圈定靶区。代表性勘探线剖面上岩石样品的微量元素特征显示, As与Au相关性最好, Sb与Au相关性次之,表明毒砂和辉锑矿是与金关系最密切的矿物,且它们在一定程度上呈互补关系,即辉锑矿发育处,毒砂较为不发育,反之亦然。毒砂可能是金的主要载体,而辉锑矿的形成对于金的富集起到了增强作用。通过综合分析成矿元素分布图及广域电磁解释剖面,明确了电阻率的突变位置与矿体分布具有很好的耦合性。在电阻率突变线附近,尤其是2 组突变交会处,发育矿体的可能性最大。在此基础上,在GY3 剖面上划分了3 个级别共5 个有利勘探区,Ⅰ级有利勘探区为浅部的主要含矿构造与横向显著电阻率突变带交会处,Ⅱ级有利勘探区为横向显著电阻率突变带与纵向突变带交会处,Ⅲ级有利勘探区为已发现M4、M6 等盲矿体以深相似构造位置即横向一般电阻率突变带。有利勘探区可向两侧其他剖面延伸,为其他剖面有利勘探区划分提供参考。Abstract: The Zaozigou Gold Deposit is one of the largest gold deposits in the Western Qinling orogenic belt. However, as mining depth increases, exploration becomes increasingly challenging. Despite the significant deep resource potential, the spatial distribution of deep orebodies remains poorly understood. This study conducts deep metallogenic prediction and delineates prospective targets in the Zaozigou Gold Deposit through the integration of geochemistry and wide field electromagnetic method. Trace element characteristics of rock samples from a representative exploration profile indicate that As exhibits the strongest correlation with Au, followed by Sb, suggesting that arsenopyrite and stibnite are the minerals most closely associated with gold mineralization. These 2 minerals show a somewhat complementary relationship—arsenopyrite is less developed where stibnite is abundant, and vice versa. Arsenopyrite is likely the main carrier of Au, while the presence of stibnite enhances Au enrichment. Comprehensive analysis of ore-forming element distribution maps and wide field electromagnetic interpretation sections reveals a strong coupling between abrupt resistivity changes and orebody distribution. The highest potential for ore occurrence lies near resistivity discontinuities, especially at the intersections of 2 sets of resistivity break lines. Based on these results, 5 favorable exploration zones of 3 levels were delineated along the GY3 profile. First-level targets are located at intersections of major mineralized structures with pronounced lateral resistivity gradients near surface; second-level targets lie at intersections of significant lateral and vertical resistivity anomalies; and third-level targets are situated at deeper structural positions, similar to those hosting previously discovered blind orebodies (M4, M6), and are associated with moderate lateral resistivity gradients. These favorable zones are likely to extend laterally to adjacent profiles, providing guidance for delineating prospective targets in nearby sections.
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