Intrusion related gold deposits in the Tanami and Kurundi-Kurinelli goldfields, Northern Territory, Australia: Constraints from LA-ICPMS analysis of fluid inclusions

Gold deposits in the Tanami and Kurundi-Kurinelli goldfields of the Northern Territory, Australia, have geological and geochemical characteristics that distinguish them from the typical vein-hosted, orogenic gold deposits that occur in other parts of Australia. This study used cathodoluminescence (CL) and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) analyses of fluid inclusions to investigate the source of mineralising fluids from both the highly mineralised Tanami goldfield and weakly mineralised Kurundi-Kurinelli goldfields in northern Australia. Cathodoluminescence showed three generations of quartz in fractured and mineralised veins from the Groundrush deposit in the Tanami goldfield but the remaining deposits had uniform dark CL images. The LA-ICPMS trace element data indicate an evolution from B-As–enriched, magmatic fluid to a highly Sr-Ba-enriched fluid which results from interaction with sedimentary rocks. The fluids from both regions have chlorinity normalised Zn and Pb concentrations at the magmatic end of the metamorphic – magmatic mixing trend for these elements. This is in agreement with previous studies showing that gold mineralisation is coeval with magmatism in the Tanami region. The relatively high salinity of the fluids in both the Tanami and Kurundi – Kurinelli goldfields, and their trace element contents indicates that the deposits in both regions are intrusion-related gold deposits. The higher gold endowment of the Tanami region may result from the multiple gold-mineralisation events in this region whereas fluid flow associated with mineralisation in the Kurundi – Kurinelli goldfields appears to be of limited extent.