TY - JOUR
T1 - Diamonds, dunites, and metasomatic rocks formed by melt/rock reaction in craton roots
AU - Pintér, Zsanett
AU - Foley, Stephen F.
AU - Yaxley, Gregory M.
N1 - Funding Information:
We thank Dean Scott, Nick Farmer, and Hugh O’Neill for support with the ultrahigh-pressure piston-cylinder apparatuses at RSES at ANU; Jeff Chen at the Center for Advanced Microscopy at ANU for help with the electron probe microanalyzer and Finlay Shanks at School of Chemistry at Monash Univerity for the help with the Raman spectrometer. This work is supported by the ARC grant FL1800134 to S.F. Foley, and a Macquarie University Higher Degree research scholarship to Zs. Pintér.
Publisher Copyright:
© 2022, The Author(s).
PY - 2022/12
Y1 - 2022/12
N2 - The thick mantle lithosphere beneath cratons consists of strongly reduced rocks that have reacted with oxidized melts. These low-silica, incipient melts are rich in CO2 and H2O and react with surrounding rocks forming an enriched zone at the base of the lithosphere, which is the source region for many diamonds. Here, we reproduce these reactions in novel experiments in which oxidised, hydrous carbonate-rich melts are reacted with reduced, depleted peridotite at 5 GPa pressure. Results explain several key features of the mantle sample in kimberlites as products of a single process, namely the formation of diamonds, phlogopite and alkali-amphibole bearing rocks, iron-rich dunites, and garnets and clinopyroxenes with pyroxenitic compositions. Initially, redox freezing occurs where melts meet the reduced peridotite, depositing diamonds and associated garnet and clinopyroxenes. The spreading reaction front leaves behind Fe-rich dunite, and crystallizing phlogopite and amphibole when the melt solidifies at the reaction front.
AB - The thick mantle lithosphere beneath cratons consists of strongly reduced rocks that have reacted with oxidized melts. These low-silica, incipient melts are rich in CO2 and H2O and react with surrounding rocks forming an enriched zone at the base of the lithosphere, which is the source region for many diamonds. Here, we reproduce these reactions in novel experiments in which oxidised, hydrous carbonate-rich melts are reacted with reduced, depleted peridotite at 5 GPa pressure. Results explain several key features of the mantle sample in kimberlites as products of a single process, namely the formation of diamonds, phlogopite and alkali-amphibole bearing rocks, iron-rich dunites, and garnets and clinopyroxenes with pyroxenitic compositions. Initially, redox freezing occurs where melts meet the reduced peridotite, depositing diamonds and associated garnet and clinopyroxenes. The spreading reaction front leaves behind Fe-rich dunite, and crystallizing phlogopite and amphibole when the melt solidifies at the reaction front.
UR - http://www.scopus.com/inward/record.url?scp=85142876180&partnerID=8YFLogxK
U2 - 10.1038/s43247-022-00630-3
DO - 10.1038/s43247-022-00630-3
M3 - Article
AN - SCOPUS:85142876180
SN - 2662-4435
VL - 3
JO - Communications Earth and Environment
JF - Communications Earth and Environment
IS - 1
M1 - 296
ER -