The Avoca Tank orebody is one of a series of copper-rich orebodies occurring within the Girilambone Cu province of central New South Wales. Mineralisation at Avoca Tank is hosted within several narrow, chloritic, greenschist-facies shear zones which developed ~430 Ma (U-Pb titanite) within metasedimentary rocks around the margins of an Ordovician (ca. 470 Ma) mafic sill complex. Mineralisation at Avoca Tank preserves an early oxide phase (sulfide barren) as magnetite-rich shears that are overprinted by a pyrite-chalcopyrite-rich sulfide phase. The mineralogical and chemical footprint surrounding sulfide mineralisation is narrow (<50 m) offering limited ore vectoring using mineralogical and chemical change. However, magnetite-rich shears occur external to and within sulfide mineralised intervals, and magnetite within these shears displays distinctive trace element variation depending on proximity to Cu mineralisation. Changing magnetite trace element chemistry with increasing Cu abundance at Avoca Tank is best represented by two ternary systems. A ternary plot of Ni-V-Ti effectively separates magnetite from unmineralised zones via Ni abundance, while the ratio of Ti to V effectively separates magnetite from low-, moderate- and high-grade Cu zones. A ternary plot of Sn (100*Sn)-Zn-Ni effectively discriminates between unmineralised, low-grade and combined moderate- to high-grade zones. The greatest control here is the ratio of Zn to Sn, but the inclusion of Ni abundance provides a greater separation between low- versus combined high- and moderate-grade ore. Many of the trace element trends recorded in magnetite are mirrored in the overprinting sulfides. We propose a two-phase mineralising system, with initial development of chemically uniform, sulfide barren magnetite-chlorite-rich shear zones in proximity to the margins of older mafic sills. A subsequent, and potentially hotter (+60 °C), fluid harvested the early oxide for Fe, with the partial replacement, recrystallisation and re-equilibration magnetite within a sulfide-rich hydrothermal fluid under greenschist facies metamorphic conditions. As many known orebodies in the Girilambone Cu province are associated with magnetite-rich gangue, magnetic surveys are an effective exploration technique. Based on this pilot study, mapping trace element variation in magnetite within these bodies is an additional ore-vectoring technique in the search for economic Cu mineralisation in this province.

Avoca Tank 矿体是新南威尔士州中部 Girilambone Cu 省内一系列富铜矿体之一。Avoca Tank 的矿化位于几个狭窄的绿泥石、绿片岩相剪切带内，这些剪切带在奥陶纪（约 470 Ma）基性基岩杂岩边缘周围的变沉积岩中发育了约 430 Ma（U-Pb 钛矿）。阿沃卡罐的矿化保留了早期氧化物相（贫瘠的硫化物），作为富含磁铁矿的剪切体，其​​上覆盖着富含黄铁矿-黄铜矿的硫化物相。硫化物矿化周围的矿物学和化学足迹很窄（<50 m），利用矿物学和化学变化提供有限的矿石导向。然而，富含磁铁矿的剪切发生在硫化物矿化层的外部和内部，这些剪切力中的磁铁矿根据与铜矿化的接近程度而显示出独特的微量元素变化。随着 Avoca Tank 中铜丰度的增加，磁铁矿微量元素化学的变化最好由两个三元系统来体现。Ni-V-Ti 三元图通过 Ni 丰度有效地将磁铁矿与未矿化带分离，而 Ti 与 V 的比例则有效地将磁铁矿与低品位、中品位和高品位铜带分离。Sn (100*Sn)-Zn-Ni 三元图可有效区分未矿化、低品位和中高品位组合区域。这里最重要的控制是 Zn 与 Sn 的比例，但是 Ni 丰度的包含提供了低品位矿石与组合的高品位和中品位矿石之间更大的分离。磁铁矿中记录的许多微量元素趋势反映在套印的硫化物中。我们提出了一个两相矿化系统，初步开发了化学均匀、贫硫化物、富含磁铁矿-绿泥石的剪切带，靠近较老的镁铁质基岩的边缘。随后的、可能更热（+60°C）的流体收获了铁的早期氧化物，在绿片岩相变质条件下，在富含硫化物的热液流体中部分置换、重结晶和重新平衡了磁铁矿。由于吉里兰邦铜矿省的许多已知矿体都与富含磁铁矿的脉石有关，因此磁力勘探是一种有效的勘探技术。根据这项试点研究，