A New Method for Assessing the Thermal History of Sediments

ALEXANDER, ROBERT, ROGER MARZI,* and ROBERT I. KAGI, Curtin University of Technology, Perth, Western Australia

A method for reconstructing the thermal history of sediments has been developed based on the thermal cyclization reactions of alkyl biphenyls. Evidence is presented that these reactions occur in sediments and that they can also be replicated under controlled conditions in the laboratory.

These studies have enabled accurate kinetic parameters to be measured for the cyclization reactions.

The approach used involves measuring the extent to which six independent molecular processes have occurred in the sediment. These measurements have been made at a number of points in a sediment column. The progress of these reactions is then calculated for this sedimentary column using the laboratory derived kinetic parameters, the known geological history and an assumed thermal history. In an iterative process the heat flow history is then modified until a match between observed and calculated progress of reaction is achieved. As a result a thermal history is determined which is consistent with these geochemical constraints and the known geological history of the sediment column.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)