澳洲帝汶海域瓦肯次盆地源自碳氢化合物的

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澳洲帝汶海域瓦肯次盆地源自碳氢化合物的
地下环境碳酸盐胶结
Hydrocarbon-derived carbonate cementation in subsurface
environments of the Vulcan Sub-basin, Timor Sea, Australia
宫守业1, 米泓生2, 吴明贤3, 国安3,
王士伟1, 周定芳3, 周颖蔚 3, 吴荣章2 3, 王玉瑞4
Shou-Yeh Gong1, Horng-Sheng Mii2, Ming-Shan Wu3, Kuo-An Lin3, Shih-Wei Wang1,
Ting-Fang Chou3, William Y. W. Chou3, Jong-Chang Wu2 3, Yuh-Ruey Wang4
1. 国 自然科学博物 地质学组,台中
2. 国 台湾师范大学地球科学系,台
3. 中国石油公司探采研究所,苗
4. 国 台 科技大学材 与矿物资源工程系,台
关键词: 碳氢化合物渗透,甲烷氧化,微生物成岩作用,碳酸盐胶结, 帝汶海
Keywords: Hydrocarbon leakage, Methane oxidation, Microbial diagenesis, Carbonate
cementation, Timor Sea

Localized carbonate cementation was found in the Eocene Grebe Sandstone of the
Vulcan Sub-basin, Timor Sea, Australia. Those cements were previously interpreted as
having resulted from microbial methane oxidation and sulfate reduction in a shallow
subsurface environment and were related to hydrocarbon leakage. In this study, we
reassessed those localized carbonate cements in the Grebe Sandstone, and obtained new
findings.
Petrographical studies showed that (1) there were two facies of sands in the Grebe
Sandstone: cemented, mostly fine-grained sands; and (2) loose, often coarse-grained
sands. In addition, there were two types of carbonate cements in the Grebe Sandstone:
(1) sparry to microsparry cements in calcareous, fine-grained sandstones; and (2)
micritic to microsparry cements in limestones. Stable carbon isotopic values revealed
that only the cements associated with sandstones were hydrocarbon-derived, and the
resultant mineral is mainly calcite. Petrography, Stable oxygen isotopic values and trace
elemental compositions of the interpreted hydrocarbon-derived calcite cements
significantly differ from those of cold-seep carbonates at or near the sea floor. Our
results support that the localized carbonate cements in the Grebe Sandstone are related
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to hydrocarbon and occurred in shallow burial conditions.
Moreover, it was noted the hydrocarbon-derived carbonate mineralization only
occurred in the fine-grained sands, not in the coarse-grained sands. In other word, the
cementation was controlled not only by hydrocarbon leakage but also by the lithofacies
of the host rock. We propose herein that the extent of hydrocarbon-related cementation
alone cannot be used to evaluate the trap integrity as previously suggested by others.

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