Thermal maturation of organic matter by a thick basaltic sill in Upper Cretaceous shales, Svartenhuk Halvø, central West Greenland

Abstract

Thermal effects of igneous intrusions on sedimentary organic matter indicate that organic compounds are more stable under geologically short but intense exposure to high temperature compared to those affected by slow burial. In the immediate contact zone a drastic reduction occurs in kerogen content, accompanied by high reflectance values. The presence in this zone of n-alkanes in the C₁₅–C₂₀ range suggests hydrogenation of kerogen. Heat effects are still recognisable at a distance of three times the thickness of the intrusive body.