Comparison of I/S Transformation and Maturity of Organic Matter at Elevated Temperatures

B. Velde and B. Lanson
Département de Géologie, UR 1316 CNRS, École Normale Supérieure 24 rue Lhomond, 75213 Paris, France

Abstract: Comparing the state of reaction advancement of I/S (illite content of illite/smectite mixed layer minerals) and organic matter (vitrinite reflectance) in instances of high temperature gradients allows one to observe the evolution of geologic materials under extreme conditions. In a geothermally heated sedimentary series (Salton Sea area, California), both clays and organics have reacted to completion in the temperature gradient range of 200°–400°C/km during heating episodes of 104 years. We observed an instance of rapid heating, through magmatic intrusion into the Meso-Paleozoic eastern Paris Basin sedimentary series in late Permian time, which induced changes in the organic material, but where clays are apparently unaffected.

Key Words: Illite/smectite • Kinetics • Vitrinite maturity

Clays and Clay Minerals; April 1993 v. 41; no. 2; p. 178-183; DOI: 10.1346/CCMN.1993.0410206
© 1993, The Clay Minerals Society
Clay Minerals Society (www.clays.org)