The notable group of iron oxide-copper–gold (IOCG) deposits at the Carajás Province (Amazonian Craton, Brazil) contain remarkable copper reserves due to a complex Neoarchean metallogenetic evolution. The overlay of diachronic hydrothermal-mineralizing events is revealed by two clusters of boron isotope compositions of hydrothermal tourmaline obtained in IOCG deposits (Salobo, Igarapé Bahia, GT-46, Grota Funda and Furnas) with (i) high δ¹¹B (+8.2 to +17.2‰) and (ii) low δ¹¹B (+3.4 to +9.8‰) values. The isotopically heavy boron signatures, recorded in tourmaline cores, are inherited from the volcano-sedimentary sequences of the ca. 2.76 Ga Itacaiúnas Supergroup, which includes exhalative tourmaline and spilites formed in extensive exhalative systems prior to the IOCG formation. During the main IOCG event at ca. 2.55 Ga, the regional circulation of magmatic-hydrothermal boron-rich fluids originated tourmaline rims and new crystals with lower δ¹¹B values. We describe the critical role of an older volcano-sedimentary as a source for boron and likely metals leached by magmatic-hydrothermal fluids to form the IOCG deposits of the Carajás Province.

由于复杂的新太古代成矿演化，位于 Carajás 省（巴西亚马逊克拉通）的氧化铁-铜-金 (IOCG) 矿床群包含显着的铜储量。在 IOCG 矿床（Salobo、Igarapé Bahia、GT-46、Grota Funda 和 Furnas）中获得的热液碧玺的两个硼同位素组成簇揭示了历时热液成矿事件的叠加，具有 (i) 高 δ ¹¹ B (+8.2至 +17.2‰) 和 (ii) 低 δ ¹¹B（+3.4 至 +9.8‰）值。记录在碧玺岩心中的同位素重硼特征是从大约火山沉积序列继承而来的。2.76 Ga Itacaiúnas 超群，包括在 IOCG 形成之前在广泛的喷气系统中形成的喷气碧玺和尖晶石。在大约 IOCG 的主要活动期间。2.55 Ga，岩浆热液富硼流体的区域环流起源于电气石边缘和δ ¹¹ B 值较低的新晶体。我们描述了较旧的火山沉积物作为硼和可能被岩浆热液流体浸出的金属以形成卡拉哈斯省的 IOCG 矿床的重要作用。