THE NEODYMIUM ISOTOPE SYSTEM AS A TOOL FOR PETROLEUM-EXPLORATION

Mineralogical, petrological, geochemical, and neodymium isotopic investigations strongly suggest isotopic and chemical exchange between authigenic silicate phases and petroleum. Alteration of organic matter, sulfur reduction, generation of aqueous-acidic solutions with the resultant dissolution of K-feldspar leads to in situ crystallization of illite and chlorite as well as neodymium isotopic equilibration between the silicate phases and petroleum. These findings are of significance not only to understand the mechanisms leading to neodymium isotopic equilibration between authigenic clay minerals in detrital sediments but also to source rock-petroleum (in reservoir) correlations, in particularly when biomarker molecules (i.e., isoprenoid hydrocarbons) have been obliterated by prolonged, severe diagenesis.