Transformation mechanism of muddy carbonate rock by the coupling of bioturbation and diagenesis: A case study of the Cretaceous of the Mesopotamia Basin in the Middle East

YE Yu,LI Fengfeng,SONG Xinmin,GUO Rui

Fig. 5. Photos and schematic diagram of cast thin sections of Mishrif Formation at 2937.65 m in Well M-46 in M Oilfield, the Middle East. (a) Panoramic scanning of a cast thin section which is dyed in red (left part) and undyed in white (right part); (b) Schematic difference of burrows and matrix; (c) Dyed, single polarized light. The field of vision is matrix that is bioclastic micrite, and the bioclasts are mainly Nuculina. (d) Dyed, single polarized light. Within the field of vision, there are matrix and burrows with obvious boundaries and different rock structures. The burrows are grain-supported. The grains are composed of bioclasts of benthic foraminifera, bivalves and echinoderm bioclasts, containing a small amount of peloids. The matrix is mudisupported, with complete Nuculina. (e) Undyed, single polarized light. The field of vision is burrows filled with calcsparite bioclastic limestone, and the bioclasts are mainly bivalves, benthic foraminifera and a small amount of peloids and echinoderms. The cementation is relatively intense, and the pores are difficult to see by naked eyes.