THERMAL AUREOLE OF AN INTRUSION AND PROPOSED MECHANISM OF ITS EMPLACEMENT INTO THE SEDIMENTARY SEQUENCE OF THE CAPE VERDE RISE

Abstract

The effect of the size and shape of the thermal aureole of intrusive bodies on the maturity of organic matter in the host rocks is analyzed. The vitrinite reflectance calculated by the vitrinite kinetic model is compared with Ro (%) measured within the thermal aureole near a well-dated intrusion in the sedimentary sequence penetrated by Hole DSDP 41-368 near the Cape Verde Rise, eastern Atlantic. The comparison indicates that the calculations based on the traditional model of the instantaneous intrusion of a magmatic body significantly overestimate the temperature and degree of metamorphic alteration of the host rocks. The proposed model assumes that the thicknesses of the intrusive bodies grow over a certain period of time. The model adequately describes the observed sizes of the thermal maturity aureoles of intrusions.