Petrography and diagenesis of cavity-fill dolocretes, Kuwait

Cavity-fill dolocretes within the palaeokarst zone of the Middle Eocene chertified dolomicrite Dammam Formation are exposed within a quarry located on the top of Al-Ahmadi ridge in southern Kuwait. They are characterised by the abundance of zoned and spherulitic dolomite. These dolocretes are formed by massive precipitation of primary dolomite into cavity-fill siliciclastics within phreatic groundwater conditions during arid to semi-arid period. Successive stages of karstification and dolocretisation are responsible for the development of two types of cavity-fill dolocretes, namely; mature and immature dolocretes. The association of diagenetic alunites with the cavity-fill dolocretes suggests that hydrocarbon seepage may have played a role in the development of these dolocretes. It is suggested that the occurrence of similar diagenetic setting within carbonate sequence may potentially affect their reservoir characteristics. (C) 2013 Elsevier B.V. All rights reserved.