Dicarboxylic acids generated by thermal alteration of kerogen and humic acids.
Significant amounts (up to 2% of organic geopolymers) of low molecular weight (LMW) dicarboxylic acids (C2-C10) have been detected during thermal alteration (270 degrees C, 2 h) of kerogens and humic acids isolated from young or ancient lithified sediments.  Their distribution is characterized by predominance of oxalic acid followed by succinic, fumaric and methylsuccinic acids.  These acids are probably released by the breakdown of macromolecular structures, which have incorporated biogenic organic compounds, including diacids, during early diagenesis in sediments.  Because of their reactivity, LMW diacids may play the following geochemically important roles under natural conditions: (1) the diacids dissolve carbonates and clay minerals to increase porosity and permeability, which enhances migration of oils and gas generated from catagenesis of kerogen dispersed in shale, and (2) the diacids may form organo-metal complexes, which are important for mobilization, transport and accumulation of trace metals in sedimentary basins.
Kawamura
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Institute of Geophysics and Planetary Physics, University of California, Los Angeles 90024, USA.
Kaplan
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IR
D003998:Dicarboxylic Acids / Q000032:analysis*; D019015:Geologic Sediments / Q000032:analysis* / Q000737:chemistry; D055593:Geological Phenomena; D005844:Geology; D006358:Hot Temperature; D006812:Humic Substances / Q000032:analysis*; D006838:Hydrocarbons / Q000032:analysis / Q000737:chemistry; D010070:Oxalates / Q000032:analysis
D003998:Dicarboxylic Acids; D006812:Humic Substances; D006838:Hydrocarbons; D010070:Oxalates