This study was financially supported by the National Key Research and Development Program of China (Grant No. 2019YFA0708501) and the National Natural Science Foundation of China (Grant No. 42172060). Professors Frieder Klein (Woods Hole Oceanographic Institution, USA) and Lu Wanjun (China University of Geosciences) are appreciated for their help during the preparation of this manuscript. Thanks to Professor Zhang Bo and Dr. Liu Siqi (Peking University) for their help with the picture processing and Dr. Susan Turner (Brisbane) for assistance with English language. We are grateful to two anonymous reviewers for their critical reviews.
Natural gas, consisting primarily of methane (CH4), has become a major source of clean energy in modern society in many parts of the globe. Recent experimental observations and discoveries of deep-sourced abiotic CH4 in cold subduction zones indicate the important ability of cold subducted slabs to generate natural gas reservoirs. However, most CH4 flux and reservoirs remain unknown and their potential is overlooked in global carbon flux estimations. Massive abiotic CH4-rich fluid inclusions (FIs) in garnet and omphacite from ultrahigh-pressure (UHP) eclogites have been found in the Western Tianshan (WT) UHP metamorphic belt, which provides one ideal case for quantification of abiotic CH4 stored in the cold subducted crust. By two methods, we assess the abiotic CH4 content stored in the Chinese WT HP– UHP metamorphic belt. Our calculations show that at least 113 Mt CH4 isstored in the WT eclogites. We also discuss the implications for CH4 reservoirs in subduction zones worldwide and speculate that the cold subduction zones may represent one of the largest, yet overlooked, sources of abiotic CH4 on Earth, which should not be ignored in the global natural resource and carbon flux estimations.
ZHANG Lijuan, ZHANG Lifei, LI Xiaowei, WANG Xiao.2023. Abiotic Methane Reservoirs in the Western Tianshan HP–UHP Metamorphic Belt, China[J]. Acta Geologica Sinica(),97(1):337-349Copy