TY - JOUR
T1 - Copper isotopes track the Neoproterozoic oxidation of cratonic mantle roots
AU - Chen, Chunfei
AU - Foley, Stephen F.
AU - Shcheka, Svyatoslav S.
AU - Liu, Yongsheng
N1 - Copyright the Author(s) 2024. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.
PY - 2024/5/21
Y1 - 2024/5/21
N2 - The oxygen fugacity (fO2) of the lower cratonic lithosphere influences diamond formation, melting mechanisms, and lithospheric evolution, but its redox evolution over time is unclear. We apply Cu isotopes (δ65Cu) of ~ 1.4 Ga lamproites and < 0.59 Ga silica-undersaturated alkaline rocks from the lithosphere-asthenosphere boundary (LAB) of the North Atlantic Craton to characterize fO2 and volatile speciation in their sources. The lamproites’ low δ65Cu (−0.19 to −0.12‰) show that the LAB was metal-saturated with CH4 + H2O as the dominant volatiles during the Mesoproterozoic. The mantle-like δ65Cu of the < 0.59 Ga alkaline rocks (0.03 to 0.15‰) indicate that the LAB was more oxidized, stabilizing CO2 + H2O and destabilizing metals. The Neoproterozoic oxidation resulted in an increase of at least 2.5 log units in fO2 at the LAB. Combined with previously reported high fO2 in peridotites from the Slave, Kaapvaal, and Siberia cratonic roots, this oxidation might occur in cratonic roots globally.
AB - The oxygen fugacity (fO2) of the lower cratonic lithosphere influences diamond formation, melting mechanisms, and lithospheric evolution, but its redox evolution over time is unclear. We apply Cu isotopes (δ65Cu) of ~ 1.4 Ga lamproites and < 0.59 Ga silica-undersaturated alkaline rocks from the lithosphere-asthenosphere boundary (LAB) of the North Atlantic Craton to characterize fO2 and volatile speciation in their sources. The lamproites’ low δ65Cu (−0.19 to −0.12‰) show that the LAB was metal-saturated with CH4 + H2O as the dominant volatiles during the Mesoproterozoic. The mantle-like δ65Cu of the < 0.59 Ga alkaline rocks (0.03 to 0.15‰) indicate that the LAB was more oxidized, stabilizing CO2 + H2O and destabilizing metals. The Neoproterozoic oxidation resulted in an increase of at least 2.5 log units in fO2 at the LAB. Combined with previously reported high fO2 in peridotites from the Slave, Kaapvaal, and Siberia cratonic roots, this oxidation might occur in cratonic roots globally.
UR - http://www.scopus.com/inward/record.url?scp=85193940481&partnerID=8YFLogxK
U2 - 10.1038/s41467-024-48304-2
DO - 10.1038/s41467-024-48304-2
M3 - Article
C2 - 38773097
AN - SCOPUS:85193940481
SN - 2041-1723
VL - 15
SP - 1
EP - 11
JO - Nature Communications
JF - Nature Communications
IS - 1
M1 - 4311
ER -