关键词: 埃达克岩, 微量元素, 弧-陆碰撞

Abstract: Based on the geochemical characteristics of adakites,the significance of the Cenozoic adakites in Papua New Guinea is discussed. The result shows that the adakites of Papua New Guinea are characterized by high Sr content(>596.80×10^-6), by strongly positive Sr anomaly peaks (average Sr/Y ratio ＞41.7) and by apparent negative Nb and Th anomalies on the spider diagram of trace elements. However, both Y and Yb contents are very low(Y≤20×10^-6 and Yb≤1.9×10^-6 respectively)in the adakites. Meanwhile, in adakites of Papua New Guinea, Mg^# values are ＞0.45 and ⁸⁷Sr/⁸⁶Sr values are generally <0.704 5. The adakites of Papua New Guinea are both located at the oceanic island arc and continental margin orogens in an arc-continent collision setting. Their distribution districts contain both worldclass porphyry copper-gold as well as hot-spring gold deposits.

Key words: adakite, trace element, arc-continent collision