首页|In situ apatite and carbonate Lu-Hf and molybdenite Re-Os geochronology for ore deposit research:Method validation and example application to Cu-Au mineralisation

In situ apatite and carbonate Lu-Hf and molybdenite Re-Os geochronology for ore deposit research:Method validation and example application to Cu-Au mineralisation

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The development of laser ablation inductively coupled plasma quadrupole tandem mass spectrometry(LA-ICP-Q-MS/MS)opens new opportunities to rapidly date a variety of hydrothermal minerals.Here we present in situ Lu-Hf and Re-Os dates for hydrothermal apatite and molybdenite,respectively.We fur-ther report the first in situ Lu-Hf dates for bastnäsite,dolomite,and siderite,and assess their potential for constraining ore deposit geochronology.For method validation,we report isotope-dilution Lu-Hf dates for apatite reference material Bamble-1(1102±5 Ma)and calcite reference material ME-1(1531±7 Ma),enabling improved accuracy on matrix-matched calibration for LA-ICP-MS/MS Lu-Hf dat-ing.The new methods are applied to the Vulcan Iron-Oxide Copper-Gold(IOCG)prospect in the Olympic Cu-Au Province of South Australia.Such deposits have been difficult to accurately date,given the general lack of reliable mineral geochronometers that are cogenetic with IOCG mineralisation.Hydrothermal apatite Lu-Hf dates and molybdenite Re-Os dates demonstrate that mineralisation at Vulcan largely occurred at ca.1.6 Ga,contemporaneous with the world class Olympic Dam deposit.Our data also indi-cates that the Lu-Hf system in apatite is more robust than the U-Pb system for determining the timing of primary apatite formation in an IOCG system.We further demonstrate that dolomite can retain Lu-Hf growth ages over an extended time period(＞1.5 billion years),providing constraints on the timing of pri-mary ore mineral crystallisation during brecciation and IOCG mineralisation.Finally,late Neoproterozoic(ca.589-544 Ma)and Carboniferous(ca.334±7 Ma)Lu-Hf dates were obtained for texturally late Cu-bearing carbonate veins,illustrating that the carbonate Lu-Hf method allows direct dating of Cu remobil-isation events.This has important implications for mineral exploration as the remobilised Cu may have been transferred to younger deposits hosted in Neoproterozoic sedimentary basins overlaying the Olympic IOCG province.

Reaction-cell ICP-MSIn-situ geochronologyLu-HfRe-OsIron Oxide Copper GoldMetal fluids

Alexander Simpson、Stijn Glorie、Martin Hand、Sarah E.Gilbert、Carl Spandler、Marija Dmitrijeva、Greg Swain、Angus Nixon、Jacob Mulder、Carsten Münker

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Department of Earth Sciences,University of Adelaide,SA 5005,Australia

Mineral Exploration Cooperative Research Centre,University of Adelaide,SA 5005,Australia

British Geological Survey,Nottingham,UK

Adelaide Microscopy,University of Adelaide,SA 5005,Australia

Fortescue,Level 2 87,Adelaide Terrace,East Perth,WA 6005,Australia

Institute of Geology und Mineralogy,University of Köln,50674 Köln,Germany

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Accelerated Discovery Initiative GrantAustralian Research Council Future FellowshipMineral Exploration Cooperative Research CentreAustralian Government's Cooperative Research Centre ProgramMinEx CRC Document

ADI RD02/260FT2101009062024/11

2024

10.1016/j.gsf.2024.101867

地学前缘(英文版)
中国地质大学（北京） 北京大学

地学前缘(英文版)

CSTPCD
影响因子：0.576
ISSN：1674-9871
年,卷(期)：2024.15(5)
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