THE INDICATORS AND BOUNDARY FOR SEPARATING DIAGENESIS FROM BURIAL METAMORPHISM
Zhao Mengwei(Institut fur Geologie und Dynamik der Lithosphare, University Gottingen, Germany)
This paper is a discussion of the paper "Study of Burial Metamorphism of the Ordos Basin, Northern Shaanxi". The indicators and boundary for separating diagenesis from burial metamor- phism and their application in the study of the Ordos basin are reviewed and discussed. The indicators including clay minerals, illite crystallinity, laumontite cement, Vitrinite reflectance, coal rank, paleo-temperatures and formation of petroleum-all these show that the Mesozoic strata in the Ordos basin are in the middle diagenetic stage, thus negating the conclusion that this area is a region of burial metamorphism.