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The geochronology of Tasmanian tin deposits using LA-ICP-MS U-Pb cassiterite dating

Citation

Denholm, JL and Stepanov, AS and Meffre, S and Bottrill, RS and Thompson, JM, The geochronology of Tasmanian tin deposits using LA-ICP-MS U-Pb cassiterite dating, Economic Geology and The Bulletin of The Society of Economic Geologists pp. 1-22. ISSN 0361-0128 (2021) [Refereed Article]

Copyright Statement

Copyright 2021 2021 Society of Economic Geologists, Inc.

DOI: doi:10.5382/econgeo.4837

Abstract

The island state of Tasmania is the most important tin producer in Australia. The spatial and genetic relationship between Tasmanian tin deposits and Devonian-Carboniferous granites, which intruded throughout the Tabberabberan orogeny, has long been understood. However, little geochronological data is available to link mineralization to nearby intrusions. In this study, we investigate the connection between 19 Tasmanian tin deposits and their potential source granites, using U-Pb cassiterite dating by laser ablation-inductively coupled plasma-mass spectrometry. Archean pegmatitic cassiterite was also characterized and used for the calibration of U-Pb ratios.

Tin mineralization in Tasmania occurred between 391 ▒ 6.3 and 359 ▒ 7.8 Ma, which is coincident with most postorogenic granites of the Tabberabberan orogeny. In conjunction with the granite ages, cassiterite ages become younger from the east of the state to the west, and tin mineralization occurred over a protracted period spanning 32ám.y. Dating of several placer cassiterite samples produced unexpected results, such as the occurrence of 374 ▒ 4.7 Ma cassiterite on eastern King Island, an area known only to contain the 350 Ma Grassy granite, suggesting a distant provenance.

Tasmanian cassiterite rarely shows evidence of Pb loss; however, some analyses are characterized by elevated Th and U, likely caused by microinclusions such as monazite, which may have a detrimental effect on cassiterite U-Pb dating. This study demonstrates the utility of cassiterite dating for understanding the origin of tin deposits in complex terrains with protracted periods of tin mineralization.

Item Details

Item Type:Refereed Article
Research Division:Earth Sciences
Research Group:Geochemistry
Research Field:Isotope geochemistry
Objective Division:Mineral Resources (Excl. Energy Resources)
Objective Group:Other mineral resources (excl. energy resources)
Objective Field:Other mineral resources (excl. energy resources) not elsewhere classified
UTAS Author:Denholm, JL (Mr Josh Denholm)
UTAS Author:Meffre, S (Dr Sebastien Meffre)
UTAS Author:Thompson, JM (Mr Jay Thompson)
ID Code:143539
Year Published:2021
Funding Support:Australian Research Council (LP160100483)
Deposited By:CODES ARC
Deposited On:2021-03-23
Last Modified:2021-04-12
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