Effects of high pressure and temperature on carbon isotope compositions of some acyclic alkanes and preservation of organic matter |
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Authors: | Jianguo Du Wanchun Wang Yueju Cui Weibin Zhang |
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Institution: | 1. Institute of Earthquake Sciences, China Earthquake Administration , #63 Fuxing Road, Beijing , 100036 , People's Republic of China jianguodu@hotmail.com;3. Lanzhou Institute of Geology, Chinese Academy of Sciences , Lanzhou , 730000 , People's Republic of China;4. Institute of Earthquake Sciences, China Earthquake Administration , #63 Fuxing Road, Beijing , 100036 , People's Republic of China |
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Abstract: | The effects of high pressure and temperature on carbon isotopic compositions of acyclic alkanes and the stability of the acyclic alkanes were experimentally investigated. The pyrolysis of lignite with water in a closed system was conducted at 400–700°C and 1–3 GPa. The carbon isotope data, variations of peak carbon and evident odd–even predominance of acyclic alkanes indicated that: (1) the high pressure retarded the maturation of organic matter and destruction of hydrocarbons, (2) n-C12+ hydrocarbons from biogenic sources could be preserved in the cool slab subducted into the upper mantle, and (3) some organic compounds might preserve the carbon isotope signals inherited from biogenic sources. The results favor tracing the origins of organic matter in mantle rocks and extraterrestrial organic matter in meteorites and the process of deep carbon cycle. |
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Keywords: | evolution of organic matter pyrolysis of lignite mantle hydrocarbons biomarker compounds |
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