An Archean Yellowstone? Evidence from extremely low δ¹⁸O in zircons preserved in granulites of the Yilgarn Craton, Western Australia

Hammerli, Johannes, Kemp, Anthony I.S., and Jeon, Heejin (2018) An Archean Yellowstone? Evidence from extremely low δ¹⁸O in zircons preserved in granulites of the Yilgarn Craton, Western Australia. Geology (Boulder), 46 (5). pp. 411-414.

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Abstract

We report the discovery of Archean (2980-2670 Ma) zircons from the Yilgarn Craton in Western Australia that record unusually low delta O-18 signatures (to -0.5%). These zircons occur in cordierite-orthopyroxene granulites that retain the geochemical signature of intense premetamorphic hydrothermal alteration. We propose a model whereby the low-delta O-18 zircons crystallized within protoliths that record multiple stages of high-temperature interaction and hydrothermal exchange between shallow crustal material and O-18-depleted meteoric fluids, in a setting analogous to that of the Yellowstone caldera. Burial and subsequent granulitefacies metamorphism of this crust led to the crystallization of zircon, which acquired and preserved the extremely O-18-depleted signature of the whole rock. The apparent absence of strongly O-18 depleted Archean zircons has been a puzzling feature of the global zircon record, but we suggest this is an artifact of poor preservation potential. Our findings suggest that long-lived, shallow crustal magmatic-hydrothermal systems similar to those operating in modern caldera complexes were also a feature of Archean Earth.

Item ID: 53649
Item Type: Article (Research - C1)
ISSN: 0091-7613
Copyright Information: © 2018 Geological Society of America.
Funders: Swiss National Science Foundation (SNSF), Australian Research Council (ARC)
Projects and Grants: SNSF grant P2SKP2_155067, ARC Future Fellowship FT10010059
Date Deposited: 16 May 2018 07:33
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040310 Sedimentology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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