巴布亚新几内亚位于太平洋板块和印度-澳大利亚板块的汇聚边缘,由3个构造单元组成。巴布亚新几内亚主要发育两种金矿化类型,即浅成低温热液型和斑岩型。2015—2018年开展的巴布亚新几内亚国家尺度地球化学填图,在高地地区、巴布亚半岛和新几内亚群岛采集了1 399件水系沉积物样品。文章研究了巴布亚新几内亚金的地球化学背景、空间分布特征和成矿潜力。巴布亚新几内亚金含量为0.2~6 188.0 ng/g,中位数(地球化学基准值)为1.5 ng/g,高于大陆地壳金元素丰度,略低于中国和澳大利亚的金地球化学基准值。由于广泛发育中酸性侵入岩、碱性侵入岩和碱性火山岩,由巴布亚褶皱带、新几内亚逆冲带、奥罗褶皱带、东部褶皱带、东巴布亚复合地体、巴布亚群岛、伯瓦尼-托里塞利地体和菲尼斯特雷地体组成的中央弧陆碰撞带的金基准值高于美拉尼西亚岩浆弧。地球化学图中,新几内亚逆冲带的钙碱性侵入杂岩体、美拉尼西亚岩浆弧中的钙碱性侵入杂岩体和富钾火山-侵入杂岩体与高金含量的区域具有高度耦合对应关系。这次工作圈定了7处金地球化学省和9处金地球化学异常区,主要分布于新几内亚逆冲带。8处异常区均具有发育浅成低温热液型或斑岩型金矿的潜力,可作为下一阶段巴布亚新几内亚金矿找矿方向。

Papua New Guinea (PNG), which is located at the convergence edge between the Pacific plate and the Indo-Australian plate, consists of three tectonic units. There are two main types of gold mineralization in PNG: epithermal and porphyry. National-scale geochemical mapping was conducted in PNG between 2015-2018, using 1399 stream sediment samples collected from the Highland Region, Papua Peninsula, and New Guinea Islands. In this preliminary study we analyzed the geochemical background, spatial distribution characteristics and metallogenic potential of gold in PNG. The gold concentration ranged between 0.2-6188.0 ng/g, with a median value of 1.5 ng/g, which is higher than the gold upper crustal aboundance, and slightly lower than the gold geochemical baselines of China and Australia. The Central Arc-Land Collision Zone—consisting of the Papuan Fold Belt, the New Guinea Thrust Belt, Finisterre Terrane, the Aure Fold Belt, the Eastern Fold Belt, the Eastern Papuan Composite Terrane, and the Finisterre Terrane, with widespread development of medium-acidic intrusive rocks, alkaline intrusive rocks, and alkaline volcanic rocks—has a higher median value of gold than the Melanesian Arc. The calc-alkaline intrusive complex of the New Guinea thrust belt, and the calc-alkaline intrusive complex and the potassium-rich volcano-intrusive complex of the Melanesian magmatic arc strongly correlate with higher gold concentration. Altogether seven gold geochemical provinces and nine gold anomalies with epithermal or porphyry mineralization potential are delineated.