Abstract
We report the discovery of Archean (2980-2670 Ma) zircons from the Yilgarn Craton in Western Australia that record unusually low δ18O 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-δ18O zircons crystallized within protoliths that record multiple stages of high-temperature interaction and hydrothermal exchange between shallow crustal material and 18O-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 18O-depleted signature of the whole rock. The apparent absence of strongly 18O 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.
| Original language | English |
|---|---|
| Pages (from-to) | 411-414 |
| Number of pages | 4 |
| Journal | Geology |
| Volume | 46 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 1 May 2018 |
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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.; Jeon, Heejin.
In: Geology, Vol. 46, No. 5, 01.05.2018, p. 411-414.Research output: Contribution to journal › Article
TY - JOUR
T1 - An Archean Yellowstone? Evidence from extremely low δ18O in zircons preserved in granulites of the Yilgarn Craton, Western Australia
AU - Hammerli, Johannes
AU - Kemp, Anthony I.S.
AU - Jeon, Heejin
PY - 2018/5/1
Y1 - 2018/5/1
N2 - We report the discovery of Archean (2980-2670 Ma) zircons from the Yilgarn Craton in Western Australia that record unusually low δ18O 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-δ18O zircons crystallized within protoliths that record multiple stages of high-temperature interaction and hydrothermal exchange between shallow crustal material and 18O-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 18O-depleted signature of the whole rock. The apparent absence of strongly 18O 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.
AB - We report the discovery of Archean (2980-2670 Ma) zircons from the Yilgarn Craton in Western Australia that record unusually low δ18O 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-δ18O zircons crystallized within protoliths that record multiple stages of high-temperature interaction and hydrothermal exchange between shallow crustal material and 18O-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 18O-depleted signature of the whole rock. The apparent absence of strongly 18O 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.
UR - http://www.scopus.com/inward/record.url?scp=85045915508&partnerID=8YFLogxK
U2 - 10.1130/G39969.1
DO - 10.1130/G39969.1
M3 - Article
VL - 46
SP - 411
EP - 414
JO - Geology
JF - Geology
SN - 0091-7613
IS - 5
ER -