TY - JOUR
T1 - Geochemical and C-O Isotopic Study of Ophiolite-Derived Carbonates of the Barzaman Formation, Oman
T2 - Evidence of Natural CO2 Sequestration Via Carbonation of Ultramafic Clasts
AU - Ali, Arshad
AU - Abbasi, Iftikhar Ahmed
AU - Nogueira, Leonardo Brandão
AU - Hersi, Osman Salad
AU - Al Kindi, Sumaiya A.N.
AU - El-Ghali, Mohamed A.K.
AU - Nasir, Sobhi Jaber
N1 - Funding Information:
The authors thank Saif Al Mamri and Ibrahim Khusaibi for their help with SEM analysis carried out at the Central Analytical and Applied Research Unit (CAARU), Sultan Qaboos University (SQU). Badar Al Waili in the Department of Earth Sciences, SQU is thanked for preparing thin-sections. The authors would like to thank Dr. Tahir Shah, VC (former) of FATA University, for useful feedback on the early version of the manuscript. The authors acknowledge the support of the laboratory staff for geochemical and isotopic measurements done at the Geochemistry Laboratory (LGQa), Department of Geology, Federal University of Ouro Preto, Brazil. The authors appreciate the valuable comments by Juan Carlos de Obeso and the other two anonymous reviewers that greatly improved the paper. The editor (Stephen Parman) and associate editor are thanked for their editorial handling.
Publisher Copyright:
© 2021. American Geophysical Union. All Rights Reserved.
PY - 2021/10
Y1 - 2021/10
N2 - Carbonate precipitation through atmospheric CO2 uptake by alkaline-hyperalkaline waters offers a potential approach to mitigating anthropogenic CO2 emissions. The Oman Ophiolite produces high-pH water characterized by continuous sequestration of CO2 at the air-water interface. The geochemical and isotopic data of carbonates from the Barzaman Formation is used to assess the amount of atmospheric CO2 stored in the dolomite-calcite assemblage. Post Archean Australian Shale -normalized rare earth elements patterns, with the exception of La and Ce anomalies, are similar to those of the bulk oceanic and lower crusts, with increasing LREE and flat HREE trends, and a positive Eu anomaly. The δ13CVPDB and δ18OVSMOW isotope values of the analyzed samples show two distinct end-members, in which dolomite (−7.77‰ and +27.3‰) is isotopically heavier than calcite (−9.93‰ and +21.5‰). The estimated carbonate growth temperatures (18°C–56°C) are indistinguishable from the previously reported range (18°C–66°C). The C-O isotope model for calcite, groundwater, and atmospheric CO2 shows that an ophiolite-derived calcite sample absorbed an unequivocal amount of atmospheric CO2 (78% ± 11%) during precipitation. At the same time, dissolved inorganic carbon (DIC) in water accounts for the remaining carbon contribution (22% ± 9%). DIC is closely associated with different carbonate lithofacies and ophiolite-derived soil, exhibiting large variations in C-O isotopic compositions caused by isotopic disequilibrium. Taken together, geochemical and isotopic properties confirm that the carbonates were formed under oxic conditions triggered by the water-rock interaction. For a reliable estimate of CO2 sequestered by carbonates of the Barzaman Formation, a systematic groundwater analysis is recommended to determine the contribution of CO2 in DIC.
AB - Carbonate precipitation through atmospheric CO2 uptake by alkaline-hyperalkaline waters offers a potential approach to mitigating anthropogenic CO2 emissions. The Oman Ophiolite produces high-pH water characterized by continuous sequestration of CO2 at the air-water interface. The geochemical and isotopic data of carbonates from the Barzaman Formation is used to assess the amount of atmospheric CO2 stored in the dolomite-calcite assemblage. Post Archean Australian Shale -normalized rare earth elements patterns, with the exception of La and Ce anomalies, are similar to those of the bulk oceanic and lower crusts, with increasing LREE and flat HREE trends, and a positive Eu anomaly. The δ13CVPDB and δ18OVSMOW isotope values of the analyzed samples show two distinct end-members, in which dolomite (−7.77‰ and +27.3‰) is isotopically heavier than calcite (−9.93‰ and +21.5‰). The estimated carbonate growth temperatures (18°C–56°C) are indistinguishable from the previously reported range (18°C–66°C). The C-O isotope model for calcite, groundwater, and atmospheric CO2 shows that an ophiolite-derived calcite sample absorbed an unequivocal amount of atmospheric CO2 (78% ± 11%) during precipitation. At the same time, dissolved inorganic carbon (DIC) in water accounts for the remaining carbon contribution (22% ± 9%). DIC is closely associated with different carbonate lithofacies and ophiolite-derived soil, exhibiting large variations in C-O isotopic compositions caused by isotopic disequilibrium. Taken together, geochemical and isotopic properties confirm that the carbonates were formed under oxic conditions triggered by the water-rock interaction. For a reliable estimate of CO2 sequestered by carbonates of the Barzaman Formation, a systematic groundwater analysis is recommended to determine the contribution of CO2 in DIC.
KW - Barzaman Formation
KW - C-O isotopes
KW - CO sequestration
KW - Oman Ophiolite
KW - carbonates
KW - carbonation
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U2 - 10.1029/2020JB021290
DO - 10.1029/2020JB021290
M3 - Article
AN - SCOPUS:85118221069
VL - 126
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
SN - 2169-9313
IS - 10
M1 - e2020JB021290
ER -