Behavior of organic matter from Callovian shales during low-temperature air oxidation

In order to study the effects of oxidation of sedimentary organic matter, l ow-temperature air oxidation experiments were conducted on a shale and its kerogen concentrate at 60 and 100 degrees C for 2-2048 h. The first stage o f organic matter alteration was marked by a decrease in the extract yield, mainly attributed to evaporation and adsorption processes. During the secon d stage, the saturated and unsaturated biomarkers disappeared from the free hydrocarbons' phase and were probably incorporated into the polar phase th rough oxygen bonds. The third stage, characterized by the formation of shor t chain alkanes, was well correlated to the increase in the oxygen content of kerogen. The genesis of neoformed oxygen-bearing compounds including car boxylic acids was also observed. (C) 1999 Elsevier Science Ltd. All rights reserved.